bum custard
Similar to fanny batter it is a product of the anus usually (but not exclusively) derived from a mixture of lubricant, sex wee and faeces. Cant imagine it smells or tastes very good but doubtless there is some mexican cheese dragon type out there who puts it on their flakes in the morning...
She was walking down the street casually letting one go when with a massive burp her anus spewed forth a massive blob of bum custard
Custard bum
A semen filled asshole.
Jason why does you're fart smell like cum, you little custard bum