Why do men lie about their age?

I had been talking to this guy over two months. I'm 22 and he told me that he was 26. I googled his aim sn and I found his old blackplanet page. It said that he was 29. Then he goggled his myspace name and he had a second page that said he was 29. I just want to know why some men feel the need to lie about such trivial stuff? if he had been upfront with me, I would have told him that I didn't date men that much older than me and we could have been friends.
Why do men lie about their age?
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