"so u gonna hit up everyone on ur facebook?" Has a deeply incoded message intangled upon it. U is also referred as you in the Internet world. Gonna is also a slang for going to. The terms 'hit up' refer to intercourse. The message simply yet subtly means. So, are you going to have sexual intercourse with everyone on your facebook?
Wow, Edwin you do have a lot of friends on your facebook! So u gonna hit up everyone on ur facebook?