i myself wish boomia might have arranged for more pranks within the hovel, but the fact is that he stayed at Pat's place and left behind a calling card. that alone is enough to exacerbate the man of pig's paranoid delusions. it's another massive L - silent, but deadly - for the fat man. it would have been hilarious if Boomia left an upper decker, an unflushed turd, graffiti, a whoopee cushion, etc. but all that matters is he stayed there and proved it. Rick can't recover from this. it also just speaks better of Boomia and the funsters, because leaving behind photos of an actor is totally harmless.
Rick, however, will only shoot himself in his pudgy feet and that will be funny all the same. if anything, Boomia's stay was respectful, and he just "accidentally" left some pictures behind. oh well, c'est la vie!
Patrick?
"REEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE YOU WILL RUE THE DAY STALKER CHIIIIIIIIIIIIIIIIILD!" as he shakes an impotent fist towards the teletubby sun.