The downside of online communications is the inability to convey tone, so it's not easy to make clear that what you just wrote was in jest or meant to be ironic. Everything written will be read deadpan, so unless you want to add "(In case you can't tell, I don't REALLY think your mother pleasures truckers)", you'll need quick little signals. Unfortunately, it's very un-manly to use most of these signals. I'll explain:
1) Emoticons. Yes, adding a smiley face can indicate that no hard feelings are met, such as "Hey, I didn't really need that kidney. : ) " A sad face can indicate that you feel someone's pain: "Sorry about what I did to your kidney. : ( " A winky face can be flirtatious! "Be stalkin' you! ;)" A shocked face can indicate surprise: "Imagine how I felt when I realized you were my stalker! :o " But any emoticon use by a man signals to the reader that deep down you need a good cry and like to eat iced cream out of the box while wearing curlers and going shopping after.
2) Shorthand. Yeah, we've all seen "LOLZ!" and "ROFL" even though the person writing it is likely not "Laughing Out Loud" or having trouble typing because they're so busy "Rolling On the Floor Laughing". More importantly, such shorthand indicates that you are in touch with your feminine side, and you like to enjoy putting little bows in your hair and skipping through the park with a parasol and giving fancy haircuts to your dog.
3) Fancy fonts. Yes, using a tiny font can give the impression you're speaking quietly, and of course a huge font, or bold, or italics, can manage tone, but it's a known fact that the only people who switch fonts while typing are angry loners with too much time on their hands.
So what do I propose if you're a guy and you want to get points across while typing online, without coming across as a girly man? I am inventing "online grunting". Here's how it works:
Happy: "Grunt grunt aaah."
Upset: "Grunt grunt concern!"
Sympathy: "Grunt, there there."
Sometimes I'm Just a Clown on the Outside But I Carry a Lot of Personal Pain: "G-g-g-grunt....Grunt-gruntle."