When a male inserts his penis AND testicles into the urethra of another male, causing the receiving male to have a "fat sack".
Guy 1: Honey,I want myself in you, but I'm tired of just anal
Guy 2:Okay, let's give me the fat sack.
Guy 2:Okay, let's give me the fat sack.
by Ballsballsballssack February 22, 2010
 Get the The Fat Sackmug.
Get the The Fat Sackmug. by Lucyyfur June 21, 2005
 Get the fat sackmug.
Get the fat sackmug. by Lade1020 March 2, 2008
 Get the fat sackmug.
Get the fat sackmug. by Marvinhanovver August 21, 2009
 Get the Fat sack of shitmug.
Get the Fat sack of shitmug. by Georgiona November 23, 2007
 Get the fat sacksmug.
Get the fat sacksmug. by Daddy Fat Sacks June 5, 2003
 Get the Daddy Fat Sacksmug.
Get the Daddy Fat Sacksmug. by beanerinotaco34 January 29, 2009
 Get the Fat Sack of Shitmug.
Get the Fat Sack of Shitmug.