The episode bigains in the cafe where Penny works, Sheldon and Rajesh are playing "Tresling" which is a combined sport between armresling and Tetris. Penny walks up to them and asks them to "Cut it the hell out" and walks away to another table to celebrate someone's bithday. She walks back to to the Leonard's table and they start to discuss wether or not Leonard is coming down to the cafe on his bithday witch is coming up later that week. It turnes out that Leonard never have had an birthday party before.
Later on Penny desides to throw Leonard a supprise party but Sheldon doesn't really understand why because he is an social moron. Penny then tries to talk him into helping her by telling Sheldon that she will draw smilies on his most valuble comicbooks, but it takes a while for Sheldon to understand the consept of placmale. Sheldon changes his mind about the suppriseparty as soon as he gets it, and they start planning right away.
Howard gets the assignment to distrace Leonard for a few hours, but he is having problem to get Leonard to leave the house so he fakes an alegic reaction so they have to go to the hospital where thing gets a bit out of hand.
When they finnaly get back to the house they are to late, the party have already ended. They you will see this video with Rajesh drinking and accualy talking to girls without eny problems and there is alot of other crazy stuff going on.
Penny fells bad and gives Leonard a kiss, and Leonard asks when her birthday is.
There was notning special with this episode but i think that the directors messed up the ending, they could have made somthing romantic instead of humour, i mean that's what the show is about, humor.
Otherwise a good episode!