Caspar Milquetoast
n. a very timid man. (From the name of a character in a cartoon.)I'm a little sensitive—not a Caspar Milquetoast, but I have feelings.He's no Caspar Milquetoast. He's quite a tennis player, in fact.
milquetoast
n. a shy coward; an effeminate male.This little milquetoast goes up to the biker, looks at him sort of sad like, and then karate chops him into a quivering pulp.Some guy who looked like a milquetoast came in and asked for a set of brass knuckles.
pipsqueak
n. a small or timid man or boy. (Also a term of address.)Shut up, you little pipsqueak, or I'll hit you.I may be a pipsqueak, but I am a gentleman.
pussycat
n. a timid male; a mild-mannered and passive male.That guy is a wimp, a real pussycat.He seems mean, but underneath he's a pussycat.
weak sister
n. a timid male.It looks like Dave is the weak sister on the team.Another weak sister and we'll have to quit. We've got to pull together.