A muscle which is attractive
by Insert Name______ February 9, 2019
Get the Buttmug. by Saiemense cat August 3, 2011
Get the Buttmug. by poopy November 26, 2003
Get the buttmug. a diseas in which you suddenly need to finger your own asshole. there are some sick fucks out there.
by Splashtastic22 January 27, 2009
Get the Buttsmug. 

