This guy I used to work with didn't work very much (tool department at Sears) but he was a real smartass.
The paint machine was screwed up one time and I was trying to match this color blue with another one, so I had two samples on a stick and I asked him which one he thought was better.
"Dude, I'm colorblind".
Bullshit, quit fuckin around and just answer me.
"Dude, I'm serious, I'm colorblind."
Do you really think your fooling me?
"Dude, I'm serious."
I still didn't believe him, but I actually found out that he was serious (for once).
Another time the same guy asked me where to take his girlfriend out to eat.
Take her for a nice steak dinner.
"Dude, she's a vegetarian"
Again, thinking he was messing with me, I told him to dump her because she sounded like a basket case.
I guess he got really pissed about that because he was dead serious. He got over it but as much as he messed around about stuff, I wouldn't have thought twice about what I said to him, so I guess it didn't really bother him.