dickhead

The glans penis.

...down, down, sinking down faster than she's so far moved, the dick head exploding up into all that wet, warm slime...

A jerk; a mean or rude person.

I don't want them Special Forces guys left out there when some dickhead is afraid to go get them.

...they have been exchanging insults in writing: "dickhead," "dillweed," "fuzzbutt," "dorkwad," "asswipe," and so forth.

A stupid or useless person.

"Watch it, dickhead!" "Hey, Stan, that's my shirt you just dropped in the snow!"