The city hosts a regional Lebowski Fest June 3-4. There will be a "Big Lebowski" screening 9 pm Friday at the TLA, tix are $15 in advance, $18 at the door.
There's a bowling party at North Bowl on Saturday at 8-12 pm, admission $25 in advance, $30 at the door.
By the way, what do you get the Dude who has everything? The official Lebowski replica cardigan, made by the company that furnished the original, is on sale for $188. This presents a moral/lifestyle conundrum -- you can look like the Dude for $188, but the Dude would never pay $188 for a replica cardigan, so actually buying one would be very un-Dude like. But if somebody bought one FOR YOU (mega Father's Day hint), that would be fine.