"screw" should not be blocked, especially given that "ass" is not. O.o
Screw can either refer to "I'm going to screw that so hard!" as in, the F-word lite,
or
can refer to "I was screwing some bolts on my motorcycle the other day, and discovered that one was made out of something more similar to cream cheese than a sturdy metal, as the dang screw broke at a very low torque specification!"
(^the latter of the two references is actually something which happened to me about 2 weeks ago! O.o)