when you take the ball sacks skin and squeeze it together in your hand to make it wrinkly like a "walnut"
by austin w. August 15, 2007
Get the the walnutmug. When a man sticks his finger up his ass-hole in order to tickle his prostate, causing an instant, extreme orgasm. The prostate (looking like a walnut) is commonly used as a sex toy for vietnamese people.
by reivergirlala January 15, 2009
Get the walnuttingmug. by Pseudonyms 6969 March 20, 2016
Get the Walnutmug. by cgp24 December 14, 2010
Get the walnutsmug. 
Get the walnutmug. Did you see Walnuts' speech last night?  You know, the one about inflation.  Did he look dead to you or what?
by Iacopus October 4, 2008
Get the Walnutsmug. 