Replacement internet lingo for 'lol' (laugh out loud)
Some weirdo's say lol in real life - and if you do an impression of someone saying 'lol' out loud you write it as lul.
if you are talking about a n00b who was lol'ing it up all day you would say how he kept lul'ing all the time.
Jack: omg my mums a fricken hoe bag bitch
Jake: ffs this kid last night came on our vent channel and he kept tk'in me n was like lulululululul