The whole idea of having a catchy headline is to seek attention and get users clicking in. With something like 'Looking for sex', you make yourself seem like a sex-crazed lunatic.
For men, some activities they should include are surfing, hiking, and live music.
For women, they should include things like yoga, acting, and fashion.
These dating headlines may seem a little over the top, but gone are the days when the profiles read, 'Looking for true love', 'where's my prince charming? Do update your profile every now and then, as people get bored of seeing the same things over and over again.
Standing out in the crowd and making a point with witty headlines, will surely help you find a match that can match your witty humor.
Have a headline which goes with your profile and sums up its gist in a sentence or two.