Mucky bum is the result of passing copious amounts of excrement and having it stick to unusually long anal hair.
I have a bit of a mucky bum this morning dude.
When you poke your girlfriend up the arse and then wipe your fingers on your sunday lunch and cook it in the oven.
After sunday lunch, i served the pudding which was a mucky moody.
When you slam it straight out of the arse straight in to the gob. Direct arse to mouth train.
That girl was filthy she let me mucky pie on the first date.
When a girl proceeds to lick our a dirty crusty bum ring, whilst having a shit next to their dog who has a life threatening tumor
I performed a mucky spanial yesterdayx