when I was 16 I'd go on /b/, start a thread w/ a tripcode, reply to it pretending to be someone else but w/ the same tripcode (making it obvious it was the same person), reply to it *again* calling myself out but still w/ the same tripcode, etc. just a thread with a million posts
all pretending to be different people and calling each other out for being the same person, but all obviously the same person. this would amuse me so much I'd run out of breath from laughing so hard (and same exact thing is happening *right now* as I'm thinking about it)
sometimes an actual person would come along and just be like "what the actual fuck is going on in this thread" and then dip but mostly it was just me choking and gasping for air because of how much I cracked myself up