Forgive me---I believe this is winging around the internet at the moment....
A woman comes home from work to find her husband hunched over the computer. When she asks what he's looking at, he replies "I'm just checking out some cheap flights". She beams at him, kisses him on the forehead and heads to the bedroom. Minutes later, she reappears, wearing the briefest of negligees and a passionate interlude ensues.
The following evening, the chap is in the pub telling his mate what had happened.
"It was really weird----I didn't even know she liked darts".