Excess Bung Mung or Shit caused by a result in bad wiping practices. In laymen terms, excess shit on or around your ass.
I took a shit and couldn't get rid of the excess bung mung...
She was performing a Rusty Trombone and mentioned i had some excess Bung Mung and continued..
A girl I met at the bar visined my Drink and thoroughly enjoyed my Bung Mung later that night....