The red hand of Ulster
This, rather crudely, is what happens when you masturbate a woman who is menstruating. I first heard it in Northern Ireland, which, I imagine, is its obvious place of origin and relates to the Ulster flag.
'Don't go there!'
'Why?'
'You'll get the red hand of ulster!'
'Why?'
'You'll get the red hand of ulster!'
Red hand of ulster
A northern irish tradition of, when your friend turns his back, SLAP HIM ON THE BACK OR ASS AT F U L L FORCE.
If you have a Northern irish friend watch ye back
If you have a Northern irish friend watch ye back
I just gave ya the old red hand of ulster!