When the 'lads' are in the pub/bar, one of them goes to the toilet and leaves their pint on the
table. Another guy picks up the 'absentees' pint and rubs the rim of the glass in between his foreskin and
bell-end, when finished replaces the pint where it laid originally. You lie in wait for the victim to return, and then piss your selves laughing when he remark how
shit the beer is!! Brilliant joke until it happens to you!