Actually, it was Wildest Bill who first said “Gotcha ya!”
Eve just made it famous.
The one post that sticks in my memory most was a sequential title post. I don’t wanna slow the board with a search, but the gist was.
What is the largest thing you have ever stuck in your Anus?
Ohhh god!! Please not my cat!
Yes Guin, but it was Eve that actually made the funny post, which is why I nominated it for the “What is the funniest post” award. See how that works? 
pan
Hey! That first thread was mine! Many interesting answers all 'round, although AudreyK wouldn’t tell, the party-pooper. 
This it totally my favorite too.
I wish I could remember who said this and in what thread, but it was about keeping sex interesting, and it went something like this: "… different techniques, different positions, different colored wigs on the goat … "
For some reason I think it was Giraffe who posted that, but I could be wrong.
I don’t know who posted it, but in a GQ thread titled “What were T. rex’s arms used for?” was this little gem:
“He could throw them up in the air and wave them like he just didn’t care.”
So far, I’ve found some great stuff from Scylla. Hilarious! His pretty funny in the Pit and MPSIMS, not so funny in GQ and GD from what I’ve heard (haven’t gotten to those 2 forums yet). Nobody’s perfect I guess. Oh, and about those groundhogs…
I could tell he was getting desperate by this point.
Another post from Scylla, this one concerning his stupidest moment with the snowplow.
HAHAHAHA
It’s true, clowns ARE intrinsically evil. 
Okay, everybody read mine because they’re funny!
First, there’s Is there a good reason that the cooks at McDonalds ALWAYS place the cooked meat pattie off center of the hamburger bun? by murphydog.
Richie Rich is a fucking cocksucker by Legomancer. If the title alone doesn’t kill you, here’s an excerpt.
And Why 0 ÷ 0 = 1 by 0rbytal. Maybe not hil-freakin-arious, but I did find it amusing that DanielWithrow managed to explain why it does not using a simple marbles example, then everyone else comes in here with a bunch of calculus and other fancy schmancy mathematics, waaaaaay overcomplicating the issue. Made me laugh.
I’m so bad about names, but one OP that was beautifully crafted and wildly funny was about an encounter with a black widow spider.
Blushes and shyly raises his hand while staring at his shoes
That would be me.
Yep, Payton’s was worth the search, for those who missed it: http://boards.straightdope.com/sdmb/showthread.php?threadid=174503
Uncle Beer’s voyage into a weird onyond, Guy Stuff, is the epitome of SDMB collective humor. Garbled due to board software change, and lengthy, but an amazing board effort at sustained storytelling.
OK, I just screwed up and made this post in a thread this one was linked to.
I just wanted to say that THIS is a thread I am going to bookmark, because it has most of the funniest posts/threads ever, and I always forget to keep track of them.
Nobody has mentioned the “prehensile rectum” thread yet have they?
And as long as I’ve been here you would think I’d have seen this legendary “Goat Porn” thread, but I haven’t. Does anyone have a link?
Aggh, why damn my Godforsaken curiosity lead me toward that thread? I have a HORRIBLE case of arachnophobia. Oh God, oh God, oh God, now I’m going to be paranoid for the next 6 days.
I never make sense. Why did my Godforsaken curiosity…
I remember that! The visual I got of a T Rex sort of sliding through the Cretaceous swamp waving it’s little stubby arms in time to the beat was hysterical. Originally posted in this thread. Although the line posted above is the best from the thread, there’s enough other assorted GQ silliness to make good reading.
Some of Sauron’s pit rants are classic. The wynn-dixie one is the 'mayfield turtle tracks ice-cream’ist, so I recommend starting with that.
I’ll never forget The Horror of blimps. Honorable mention also goes to several things I’ve read from Billy Rubin and Typo mna, and there’s a ton of hilarious things I’ve read that are so funny I immediately forget them (that ever happen to anyone else?), but the funniest post that has stuck with me the longest…
…I can’t remember who posted it (for some reason I want to say JimmyNipples) but it was in a GQ thread a loooong time ago where someone was asking “Why shouldn’t you eat salicia gel?” (or something like that) and this guy goes off into a whole descriptive paragraph about how the stuff turns you into a woman. The funniest line I remember that almost made me choke was…
[paraphrased until the quotation marks]
And then it dries up all your non-skeletal muscles and they shrink up inside of your body. Guess who that is? “You guessed it, Junior and the boys!”
If anyone else remembers this and can find a link I’ll give you a high five. :D.