Roommates Square Off in The Large Hadron Collision (The Big Bang Theory, Season 3 | Episode 15)

Warning: Episode Spoilers Inside! Read at your own risk!

After Sheldon explains the scientific equivalent of "Neener-Neener," Leonard reveals that Caltech is sending him to the CERN Supercollider in Switzerland. More important, Leonard is allowed to bring a guest. Naturally, the revelation sends Sheldon into fits of ecstasy as he rushes off to begin packing.

Except Leonard isn't taking Sheldon but instead Penny for what he hopes to become a romantic Valentine's Day incursion amidst the Swiss Alps and, you know, visit the Large Hadron Collider.

Leonard arrives home to discover Sheldon enthusiastically packing for the voyage he won't be taking. Sheldon even invites him into his normally off-limits room with a cheerful, "Of course, my good friend. Come in!"

Leonard's revelation that Penny is his intended guest is at first met with disbelief, followed by typical derision. Suddenly, the most interesting collision is not among those at the Large Hadron Collider (LHC), but between the Valentine's Day plans of Leonard and the childhood dreams of Sheldon.

"We're going to Switzerland to see the CERN Supercollider. And skiing, we'll also go skiing," Leonard reveals to Penny a short time later.

Her excitement (about the skiing, not the LHC) is quickly confronted by Sheldon. Fingering the pages of Leonard and Sheldon's binder-encased "Roommate Agreement," Sheldon reveals a clause dictating that Leonard is bound to invite him for the trip.

When Leonard still rejects, Sheldon ignores his part of the agreement by engaging in a surprising bit of Tuvan throat singing, at least as his first step in convincing Leonard to change his mind.

After Leonard and Sheldon later engage in a travel game of "Traitor" (in which Sheldon reveals his distaste for Rupert Murdoch because he owns FOX and they cancelled the show Firefly), Sheldon proffers 30 pieces of silverware to Leonard in the cafeteria--a sly reference equating Leonard to Judas Iscariot.

Failing to change Leonard's mind even still, Sheldon attempts a different strategy. Leonard is awoken to a meticulously prepared breakfast in bed, replete with Frodo pancakes and gentle flute playing.

Collapsing plans to kill Leonard with kindness leave Sheldon with only one alternative--bully, embarrass, or otherwise arouse pity in Penny. The ploy works and her mercy on Sheldon leads to an ever rare hug from the physicist.

The embrace turns out to be Sheldon's downfall, however. Leonard invites Sheldon to the LHC after Penny becomes ill with the flu only to discover that now, too, Sheldon has fallen sick due to Penny's hug imbued germs.

The episode finale is prompted with the entrance of Leonard and Rajesh, as they make themselves comfortable in a Swiss hotel room.

Leonard's demure is Rajesh's delight--the room is laden with romantic perks including roses and chocolate, all contributing to Rajeh's proclamation that he will never forget the best Valentine's Day he has ever had.