(Season 4 Barney's Sidecar) Andy:"Aunt Bee, we don't wanna kill him! Maybe hurt him a little, but we don't wanna kill him!"

(Season 4 Citizens Arrest)Gomer:"Stop! Stop! Barney stop! Barney stop! Citizens arrest! Citizens arrest! Citizens arrest!" Barney:"What are you yellin' about!?" Gomer:"Like you said, you broke the law by makin' an illegal U-turn, an' I hereby as a citizen of the town of Mayberry an' the United States of America arrest you!"

(Season 5 Opie Loves Helen)

Deputy Barney Fife:"Well if it aint Daddy long legs."

Sheriff Andy Taylor:"What's that supposed to mean!?" Deputy Barney Fife:"You know what it means!"

(Season 1 The Manhunt)

Barney stops his mom at roadblock and frisks her. Mrs. Fife:"But Barney, I’m your mother." Deputy Barney Fife:"Sorry. But you might be the criminal disguised as you. Us lawmen can't afford to take any chances."

(Season 1 Opie's Charity) Opie:"Pa? What are we havin' fer supper?" Andy:"Well, you an' Aunt Bee are havin' fried chicken.. an' I'm havin' crow."

I like watching for "Bloopers" and retakes. In the episode where the gold shipment comes to town, there are two different sets of "T-Men", and when Barney goes to the Hotel it is raining and his raincoat is wet. When they cut away and come back, his raincoat is dry. 
In the episode where Barney recites "The Preamble" and messes up his hair, they cut away and come back and his hair is combed again.
I'm sure there are more and to me they add to the show and make it funnier.

Andy:"Well, were you drunk when Barney arrested you?"
Otis:"I don't know! I didn't have my glasses on!"

LOL!!!
Season 1, Episode 20

Andy:"Otis can I get you a cup of coffee?"
Otis:"No thank you! I don't drink coffee. It's bad for my liver."

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(Not sure the Season or episode) Andy: "I don't know why I keep gettin' my own britches caught on my own pitchfork!"

(Season 4 My Fair Ernest T. Bass) Andy - “You lived with a possum and a raccoon?”
Ernest T - “Sure! That’s where I learned to wash my food before I eat it."

(Not sure the season or episode)

Andy:"What did you get them?"
Barney:"Septic tank."
(pause)
Andy:"You're a fine son Barn."

(Season 4 The Sermon For Today) Barney:“Yes Sir, that’s one subject you just can’t talk enough about… sin!” (Barney didn’t even hear the sermon because he was nodding the whole time.) Andy:"He didn't talk about sin!"

(Season 5 A Date for Goober)

Barney - “You were on your date already?”
Goober - “Yeah, and it sure went fast and I followed all the directions.”
Barney - “Goober, you were on a date; you weren’t taking medicine.”

(Season 2 Keeper of the Flame)

Barney Fife:"Andy I'm tryin' to tell you somethin' an' it's very important." Andy:"Hold on. Wait a minute. Maybe you won't have to. Jubel Foster yer under arrest!" Jubel:"Huh!? Under arrest, what for!?" Andy:"For runnin' a still, an' settin' fire to yer own barn. An' ain't that the finest way for a fire to spread every which way, when it hits that alcohol!?"

(Season 5 Otis Sues the County)

Barney:"I'll just put this away in case we need it." Andy:"Like right now!" Barney:"Huh?" Andy:"Our friend Otis Campbell and Neil Bentley are suin' us for $5,000.00!"

(Season 3 Barney's First Car)

Thelma Lou:"Can you drive me out to the Johnson's some time-" (sees steering column rising out of the wheel)"Barrrney?"

(Season 5 The Lucky Letter)

Barney:"Norbert, back it up! You're on my foot! You're on my foot! Norbert you're a... Ope, you better go on in the courthouse. You're cramping my language. You know what you are, don't you Norbert?"

(Not sure of the episode or season) Barney:"****-a-doodle-do!" Andy:"You wanna get up Barn? I wanna see if there's an egg in the chair."

(Season 5 Three Wishes for Opie) Barney:"Gentlemen, I have the following announcement to make! Count Istvan Teleky exists!!!"

(Season 2 Opie's Hobo Friend)
When the hobo told Andy he should just let Opie decide for himself how he wanted to live…
Andy said, "No, I'm afraid it don't work that way. You can't let a young’n decide for himself. He'll grab at the first flashy thing with shiny ribbons on it. Then when he finds out there's a hook in it, it's too late. Wrong ideas come packaged with so much glitter that it's hard to convince them that other things might be better in the long run. All a parent can do is say 'Wait' and 'Trust me' and try to keep temptation away."

(Season 5 Man in the Middle)

When Barney & Thelmer Lou have a fallin' out: 

Barney:"So deep a friendship hath one man for another, that no female caress shall ever tear it asunder. Boy, the guy that wrote that must have been some kind of a nut!"

(Season 4 Citizen's Arrest)

Gomer:"You can just go up an alley and holler fish!!"

(Season 1 Ellie Comes to Town)

Emma Brand:"Sheriff, I come to report a murder."

Andy:"A murder?"

Emma:"That's right."

Andy:"Somebody's been murdered?"

Emma:"Yes."

Andy:"Who?"

Emma:"Me!"

Andy :"You?"

Emma:"Yes, and I'll tell you who done it! That lady druggist, that's who!"

Andy:"Miss Walker?"

Emma:"She's the one. Now, Sheriff, go arrest her. Do your duty."

 Andy:"Well, now, Emma, they's...they's just the teensiest little technicality involved here. You ain't quite dead yet."

(Season 2 The Jinx)

Barney:"Fly away buzzard 
fly away crow 
way down south where the winds don’t blow
rub your nose 
and give two winks 
and save us from this awful jinx."