I've always found quicksand (particularly the kind in Gilligan's Island reruns... which might make it mildly sexual because of Ginger and Mary-Ann) to have a a weird sexual thing about it.
Another one, usually in horror movies, is vines that grab people, like in one of the Evil Dead movies.
Another one, usually in horror movies, is vines that grab people, like in one of the Evil Dead movies.
