The dangers of modern communication is the loss of context.
I'm talking about email/msn - all the different kinds of written communications that people do nowadays.
I'm always getting in trouble when people don't know whether or not I'm joking or being sarcastic or whatever. Things that work when you're actually speaking to someone can often cause 'the uncomfortable pause' when written down.
I think I'll stop typing any kind of joke or wisecrack until someone comes up with the ESP version of MSN...