Not the funniest but one of Steve Martin and Rob Reiner's funniest.
Put a muzzle on Tits Malone, PI

No particular order. 1 My Man Godfrey (W Powell), 2 Holy Grail, 3 Young Frankenstein, 4 Groundhog Day, 5 Being There.

In no particular order :
Young Frankenstein
Ghostbusters
The Jerk
Three Amigos
Some like it hot
Pee Wee's big adventure
..personal faves :Limpet ,Reluctant Astronaut,the odd couple , monkey business , Harvey , best in show, hard day's night, elf, Taladega nights etc

Zoolander
The Jerk
Hot Rod
Blazing Saddles
This Is Spinal Tap

It's in my top five - in no particular order -
The man with two Brains
The Life of Brian
This is Spinal Tap
Thicker than Water (Yes I know it's a short)
What's up Doc.

1 - Life of Brian (How would any one bit this? Sometimes I laugh by myself just remembering some scenes).
2 - The Man with Two Brains and The Jerk.
3 - Arsenic and Old Lace ( I was surprised watching it late at night some years ago. How such an old movies was so politically incorrect?)
4 - Every movie with Mel Brooks. Specially "The Producers". Only hi would get away with jokes about Hitler.

Cool.

I have to admit, I didn't much care for Reiner's and Martin's previous collaboration 'Dead Men Don't Wear Plaid', even though it worked quite well as a noir satire.
When I sat down to watch 'Brains', I got the feeling it was already off to a bad start. I got the humor, but it didn't really click with me. Especially during Jeffrey Combs' part, I thought to myself that I should just rewatch 'Re-Animator' instead.
But somewhere within the second act, it suddenly started to grow on me. Maybe it was the 80s synth soundtrack (spot-on and somehow still out-of-place), maybe it was Martin's character transformation, maybe I just got into the mixture of deadpan goofy humor and tongue-in-cheek slapstick (if that's not an oxymoron) over time.
At times, Martin's Dr. Hfuhruhurr felt like Nielsen's Frank Drebin, just a lot less PG.
Definitely a recommendable mad doctor satire made by people who love the respective B movies.

This one's still in my all-time top 10 comedies too. Some of it (well, a lot of it) is goofy, but that's exactly why I like it. The saliva hand-cups while he's sliding across the wall, the shoes flying up in the air, the "citizen's divorce e pluribus unum," Dr. Necessitor, the drunk driving test, the cheesy 80s electronic music, his deformed killer shuffle after he tries to strangle Stepfanie Kramer ("Hunter"), and more.

Oh my! Love and Death! My first boyfriend and I went to see this at the Cinema 150 in Little Rock - that was the ONLY place to see a movie back then. He was a Woody Allen fanatic and he turned me into one! Sadly, the Cinema 150 is no more. I cried when they closed it. I'd had a lot of great movie-going experiences there: Jaws, Titanic, The Poseidon Adventure, Star Wars, Raiders of the Lost Ark. sigh
"Well, make something up!" (RG)

My top 5 in no particular order are
Vacation (Chevy Chase)
Love and Death (Woody Allen)
The Man With The 2 Brains
Take the Money and Run (Woody Allen)
Naked Gun

It is definitely in my top 5. Comedy is a very personal thing - what one person thinks is funny, someone else will think it's insipid and childish. I can't help but love pure goofiness. I watched Dead Men Don't Wear Plaid last night on HBO and was laughing so hard, I risked waking my family. TMWTB is just as funny. Seeing David Warner do such silly stuff, for such a serious actor - I loved it!
In no particular order, my top five are:
Dead Men Don't Wear Plaid
The Man With Two Brains
Some Like it Hot
Step Brothers
Tie - The Love Guru and Year One (I think the critics and most people hated these two, but I thought they were brilliant in their own way).
What are yours?