Frenulum on clit is really hot when there is lots of precum. Then lick her clit clean afterwards. Coats my mouth in silky goodness.Love it. I have done it several times with a gay friend. Unfortunately, even though he is the only guy who knows I cross dress he is not into CDs so I have to wear men's underwear when I visit.
I'm also a fan of rubbing my frenulum on a clit. Frotting and tribbing at the same time in a fashion.