Trailing is the sexual act of when you rub your
pink finger against another man's anus, until they release poo onto
the finger nail. They then
leave it to dry, before scraping it off with their teeth.
Harry: I was out
with the lads yesterday, when Colby suggested I tried to grail with Dan! To be honest, his poo tastes so nice!
Barney: Gotta love a bit of Grailing on
the weekend! HU!