Leeches! (2003)

Director: David DeCoteau

Cast: Matthew Twining, Josh Henderson, Stacey Nelson, Alexandra Westmore

When a crop of doped-up athletes from the Lakecrest College swim team dive into the campus lake to blow off some steam, the bloodsucking leeches below the surface undergo a stunning transformation. After ingesting small amounts of the swimmers' steroid-laced blood, the slimy creatures grow to unusual sizes and set out to sink their teeth into an unsuspecting student population.