Raj meets a girl with selected mutism (like him) and she can't speak to him, but over text they arrange a date. Howard agrees to go with Raj to be his voice (like usual lol), but he forgets to tell Bernadette. Bernadette goes out with Amy and Penny, while Raj, Howard, Raj's date and her friend (who acts like Raj's date's voice, a bit like Howard does for Raj) all go out, and (unknowingly) go to the same place (which doesn't serve alcohol). The girls are looking round and Bernadette sees Howard, Raj, Raj's date and her friend and hears Howard elling one of the girls she is beautiful. Because Bernadette doesn't realise that Raj got him to say that to this girl, she thinks that he is on a double date with Raj, and she leaves in tears, packs up her things and goes to stay at Penny's for a while.
Howard didn't see Bernadette and goes home, and his mother tells him that Bernadette has left, and then he leaves to go find her. After walking round for the whole night trying to find her, he goes to Sheldon and Leonard's to ask them if they have any idea where she is, but on the way he sees Penny, who says something (which I won't put on here of course), punches him and goes into her apartment. Howard follows her and sees Bernadette in the apartment. He trys to explain but because he's in pain he only gets out the words of "Beautiful...Girl...Date" instead of what he was trying to say which was "I said you're beautiful to that girl because it was a date for Raj!". However, Bernadette is even more upset and leaves. She takes a taxi to the train station to go see a relative and to leave for a while and thinks her and Howard's relationship is over. However, Howard talks to her normally again and explain what happened and saves his relationship just in time.
Sorry, it's random but there you go :D