... aha, I had the occasion to do that today. And some months ago.
Months ago : I'm telling the friend, over MSN, that I cannot do something he's asking me to do (Skype conversation). He asks me once why. I say I can't. He asks me again and again, to which I always answer that I can't. I didn't want to make up an excuse, I didn't want to Skype that day, and he made me mad with his insisting.
Today was funny though.
For those who have MSN and chat with it, you must know about the "MSN Screen name" thing that lets you change the message people see associated with your name... some leave their e-mail adress untouched, some get creative and change the message along with their mood. Mine is currently my internet pseudonym (this is the part of the name that never changes so that people know it's me) and then a sentence "If we're still friends, you sure ain't showing it" (in French).
I had one female friend ask me who it was meant for. I told her not for her since the French spelling for male friend is "ami" and female friend is "amie" and I put "amis" in the screen name (I hate spelling mistakes

) . She left it at that.
Another friend, however ? He asked me who that was for, hinting he might know. I said I wasn't going to tell him, just that it wasn't for him anyway. He asked again. I said "Hmm, you're curious today!". He lets some time pass and he says something else, and I "lol" to it or something. Then he has the audacity to say something like "Hey, it's not complicated, I asked you who it was meant for. Now, you tell me!" . I answered : "Hey, it's not complicated, I'm not telling you and I'm going to do my dishes." Rude, rude, rude.
Now, don't you hate it when someone insists you say something like that ? The friend who did what I'm relating above does this sort of thing all the time. To me it's not enough to call off the friendship, but from now on, no replies, no excuses, and a ban for some time if he does that again

!
Your opinions and stories ?