Got some humorous Winchester-thingies :-)

There's just the one (http://ficwriter1966.livejournal.com/273163.html): "So let's join the boys, out in the woods in the middle of a snowstorm, fresh from killing a nasty, hairy sumbitch that's a lot more trouble dead than it was alive."

Fighting words (http://community.livejournal.com/spn_summergen/98053.html) (my favorite): "Sam and Dean have both been through many trials, together and apart. They have lost faith. They have lost hope. They have even lost their lives. And, on more than one occasion, their dignity. "

and my tags for some more things to look for (http://delicious.com/marlowe97/humor+pre-series)

My favorite wee!chesters story!
Summer Camp (http://gigglingkat.livejournal.com/152650.html)
Summary: "I sent his brother to summer camp," he explained. "You heartless bastard," laughed the manager. "That seems to be the general consensus," John agreed.
There is a link to the podfic version on that page--really, that is the best way to experience this fic ;-)

That story was hilarious!

My favourite humorous TeenWinchester:
How Do You Exorcise the Goth from a Teenager? (John Really Wants to Know) by zannes

http://zannes.livejournal.com/17737.html

Due to a laundry mishap and an off-hand comment by John, Sam takes a walk on the Goth-side.

Ah. Goth Sam is awesome.

How about these:

Behold the Power of Pancakes by Paperbkryter
http://www.fanfiction.net/s/3382581/1/bBehold_b_the_bPower_b_of_bPancakes_b

Butting Heads by Somebody Once
http://www.fanfiction.net/s/3494259/1/bButting_b_bHeads_b

Pan Fried by BlackWingBird
http://www.fanfiction.net/s/3306386/1/bPan_b_bFried_b

No Refills by MinkMix
http://minkmix.livejournal.com/132588.html#cutid1

Also, second on Summer Camp!

Thank you! Especially loves the pancakes one.

I have one, if you don't mind self-recs. Here: http://www.fanfiction.net/s/5067837/1/Of_Mice_and_Men

Now I see where Dean gets his fear of rats from.

For Wee!chesters involving Bobby, you should check out Lampito's "The Way of things" http://www.fanfiction.net/s/7064419/1/The_Way_Of_Things
And, I know this isn't exactly what you asked for, because it involves de-aging rather than actual pre-series, but it is super funny. Lampito's "You Gotta Be Kidding" http://www.fanfiction.net/s/7335583/1/You_Gotta_Be_Kidding

Thank you for your recs, I can't wait to read them.

Two Little Ducks (http://kellifer-fic.livejournal.com/153945.html#cutid1)
Summary: John finds out just what Dean gets up to on a Friday night.

Special (http://www.fanfiction.net/s/2826655/1/Special)
Summary: At a parent teacher conference, a principal expresses some concerns to John Winchester. His sons are special... very, very special.

Loved, loved the Two Little Ducks story. Thank you for your recs!

hi! I have 3 short, funny gen stories...
Dean gets injured on a hunt, and when they go to a diner, people think that Sam is his boyfriend (which he is absolutely NOT) and abusing him (which they find hilarious, esp. Dean who can totally kick Sam's ass thank you very much!)
http://spnkink-meme.livejournal.com/590.html?thread=267342#t267342
Sam/Dean as kids - why is it not an insult, when Dean calls Sam "bitch"?
http://www.fanfiction.net/s/5331888/1/Bitch
and another kid Sam +Dean,where it turns out that Dean is just as smart as Sammy is, no matter how hard he tries to deny it.
http://www.fanfiction.net/s/3420992/1/Apples

Two great Weechester fics by the amazing CaffieneKitty:
'Anything But Ordinary': http://caffienekitty.livejournal.com/149722.html
'Carjacking': http://caffienekitty.livejournal.com/205992.html

(I also second 'Fightin' Words'. Refers to pre-series, even if it doesn't take place then.)