"I've just dropped my Mrs off at the Fanny mechanic for her check up"
Wiping your hand around you're girlfriends axe wound to check for dampness like a plumber checking for a leak in a pipe. Perfect way to check if she has been playing away when out with the girls.
"She stayed out till 4 am so I gave her a plumbers wipe to make sure she hadn't being doing the nasty"