Awkward Situation

I was with 5 friends, someone brought this new guy, I almost punched him

>What do you do for living
IM
>What's that?
I work from home on a computer
>Cool I am a programmer, what exactly do you do? who do you work for?
...well...I do different things...I don't know
>So you don't know what you do for living? lol, I don't get it?
...It's hard to explain buddy, just leave it
>Trust me I will understand, I create software
>It's very common question, how to you pay the bills ???
Do you want me to login to my bank account and show you?
>No need to be rude, I am having a friendly conversation...

How to deal with this situations? I've been through similar shit 100 times. People assume the worst if you're vague and I don't like showing off.
What do you say when they ask about your work?

there was an awesome scene in mission impossible or another Tom Cruise movie where he deals with the situation when he couldn't reveal that he was a secret agent by reviewing a fake job that made everyone jealous because it was a much better job than what everybody else had at the party

Obviously I wasn't there so I wouldn't know, but maybe he was actually interested?

It's actually pretty cool what we do for a living and a lot of my friends wanna know about it, just look at why everyone's on this forum. They wanna learn.