To casually pick your bum with your finger then smear the broon under the nose of some wee nugget.
The body builder poop tashed everyone at the gym.
to wipe the remains of a ridiculously wet fart under an unsuspecting victims nose
she had a face like an arse so i poop tashed the silly split arse
The poor excuse for a young adolescent boy's mustache. Kind of looks like he's just stuck fluff on his top lip, and tried to pass it off as puberty.
'Did you kiss him?'
'No he's got a vile poop tash!!'
To put your finger up your arse and wipe it underneath someone's nose (the moustache area).
Heather gave Amy a nice, thick pooptash as she slept.