Paddy and Mick are walking home after a night on the p*ss. They've got no
money to get a taxi and are staggering all over the place when they find
themselves outside a bus depot.
Paddy has a brainwave and says to Mick "get in there and steal a bus so we
can drive home and I'll stay out here and look out for the police"

Mick duly breaks into the depot and is gone for twenty minutes while Paddy
is wondering what the hell he is doing. Eventually Paddy sticks his head
around the door and sees Mick running from bus to bus looking very
worried.

"what in all hell are you doing Mick, get a move on!" to which Mick
replies
" I can't find a number 7 anywhere Paddy" where upon Paddy, holding his
hands to his head in disbelief, shouts " You f....... idiot Mick, steal a
number 9 and we'll get off at the roundabout and walk the rest of the way!"