Winner's peek

[Soh]

Hi,

You are playing Hold'em. You check on the river. He bet. You have nothing, so you fold. Then he peeks his hold card(s), and muck. He wins the pot.

My questions are...

What does this peek mean?

and

Why does he peek?

Thank you.

Soh

p.s. ...I don't like the peek[img]/forums/images/icons/mad.gif[/img], and I don't know why[img]/forums/images/icons/confused.gif[/img]