Cinq à sept is a French term for a visit to one's mistress...Cute name for stuff you do discreetly with someone other than your spouse between five and seven o'clock so no one notices...
James: I have a cinq à sept with a bitch ha!
Colleague: You have a mistress!! Unbelievable...Well, have a good cinq à sept!
James: Yeah! (kick in the balls)