Guy's Behavior

Why do his friends tease him in front of me?

Perhaps they (it's actually mainly one of the guys) do it too even when I'm not around, I'm not sure. He doesn't act like it bothers him though.
Recently that guy started talking about me too, like 'she should be doing this and that' and in that situation the guy almost always come in my defense saying 'you don't really know her, maybe she's a reason for doing that'... It goes like that whether I'm there or not or so I've heard.
Now that stupid friend of his started hinting about the two of us getting together (the guy and me). The guy was with hiccups for 2 days once, and I asked if he had tried the glass water thing or maybe him surprised/ scared by something would do the trick. He replied that he had drunk 2 bottles of water already but didn't know about the being scared thing. Then his friend said to me "why don't you confess to him, just tell him that you love him! His hiccups would be gone in an instant!".
The guy just mumbled something in complain and took off and I didn't really say anything but starred, lol.

Is his friend just a moron or what? He's actually married and over 50 years old but seems to act like a boy sometimes.
Why do his friends tease him in front of me?
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