i will/wanna do u
HotGurl: What do u want to do?
HotGurl: IWDU2 :)
Short for iWillDestroyU, which is very fun to say in a deep voice to small children to scare them. Also sometimes short for i Would Do You and other fun sexual phrases ;) The "i" is lower case in reference to the very popular apple devices.
Boy texts to girl: "iWDU" meaning iWouldDoU. Girl text back "iWDU first" meaning iWillDestroyU first and take all your money and your car and crush you emotionally leaving you just an empty suicidal shell.