The Big Bang Theory Season 7 Spoilers: Watch Leonard call out Penny for her drinking problem on Valentine's Day

The Big Bang Theory will air its Valentine's Day episode, "The Locomotive Manipulation," on Thursday at 8 p.m. Eastern. And as usual, Leonard finds a way to make things uncomfortable between himself and Penny on what is supposed to be the most romantic day of the year.

The two decide to have a quiet weekend at home while Sheldon and Amy double date with Howard and Bernadette, who decided to take a train to Napa Valley. (Side note: Sheldon is clearly going to be more interested in his true love, trains, then he'll be interested in Amy.) But Leonard manages to fumble the ball when he calls out Penny for her drinking in front of the rest of the group.

Bernadette suggests that the couple join the others for the Napa trip, but Leonard replies, "I'm not sure it's such a great idea to take Penny to where wine comes from." Penny, who of course happens to have a glass of red wine in her hand, glares at him while everyone else laughs. "What? It's a joke," he tells her. "Come on, we bust on each other! I wear dorky glasses. You might have a problem. It's all for laughs." Penny retorts, "That'd really piss me off if I didn't have a buzz going on."

Also in the scene, which you can view via E! Online, Sheldon and Howard discuss if they might wear the same pocket watch on the train. Sheldon, of course, believes "it would be embarrassing."

What do you expect to happen in this episode? Let us know in the comments below.