When someone sticks their finger down the crack of their butt and then swipes it across someones nose. Same technique as a wet willy. Pronounced But-twilly.
I gave Ty a buttwilly today after working out, I bet he can still smell it!
by Amazoncountry November 09, 2011
1 more definition
Physical reaction to a disturbing thought or image. The thought itself makes one physically pucker their ass muscles due to the actual thought.
When I thought I would have to hear Kenny G in concert, I immediately got the butt willies.
by JC Sears March 18, 2005