Make him squirm in public by sucking his finger as though it's a small penis.Lean forward so no one else can see you, maintain eye contact, hold his finger in your mouth, and swirl and lick and suck until he can't take it any longer. Unless you're lavishly licking up and down his finger like it's a lollipop, it is relatively easy to get away with it without being arrested. In other words, keep most of the action happening inside your mouth (even if there is a lot happening in his jeans).

Return the public humiliation by lifting her hand to your mouth as though you're going to kiss the back of it, then turn it over and burying your tongue in her palm. As with the above, do it like you were giving her oral sex. If you hold her hand at an angle and keep most of the tongue action close, Aunt Betty could be watching and simply think you're being romantic. Well, she will until your girlfriend literally slides off her chair.