Jeepers Creepers 2 showed some dick from high schoolers urinating on top of a school bus as I recall. You also got shirtless scenes of Al Santos (aka Johnny from Gross Pointe) whose acting career came to an abrupt end after appearing in that D-list horror sequel. That film was also memorable for its casting of the actor who played Leland Palmer from Twin Peaks.
Also check out Matt Dallas's first appearance on film in Camp Slaughter (2005). This super campy horror film features lots of muscly teens in 80s short shorts among them Jon Flemming.
While not inherently sexual, if you are looking for a creepy/disturbing horror film check out Bugcrush (2006) if you can find it, it was a low budget independent film directed by Carter Smith. This was by far the most disturbing film I have ever sat through, it will seriously make you squirm and keep you up at night; a true horror film.