you and whose army?

You and whose army? — Кишка тонка! А живот не надорвешь? (...)

If somebody threatens to use force against us, we can show our scorn with this Oh yes, you and whose army?
The phrase is used ironically (in reply to a threat), to suggest that we do not think the person who is speaking to us is capable of doing sth, especially fighting; that the person is too weak by himself or herself to carry it out {becoming old-fashioned?}

Example 1: If you don't shut up, I'll hit you! — You and whose army? -- ...А кишки не надорвешь? Кишки не лопнут?

Example 2: If you look at my girlfriend again, I'll kill you! — Oh yes, you and whose army? — ... Ты-то? Ой как страшно, ой как напугал.

Example 3:
BRUCE: Now I'm going to have to teach the rest of you guys a lesson.
HOOD:Yeah, you and whose army?
BRUCE:Just me... and me...
(Bruce Almighty, 2003)

It is sometimes used humorously between good friends.