When they arrived at Sheldon's office, Sheldon obviously didn't want them to go in so told them "goodbye". But Leonard insisted that they should let Dennis take a look.

When they went in, Dennis found out Sheldon was doing work in quantum loop corrections and after a moment, he pointed out there was something wrong in Sheldon's theory.

Sheldon couldn't do nothing but felt embarrassed by being corrected with a 15-year old boy on the work he had been always proud.

Also, Dennis told Sheldon he broke Sheldon's record to be the youngest person to win Stevenson Award.

Leonard left and said something really runny to Sheldon.

"It's like looking into an obnoxious mirror, isn't it?" 

obnoxious: unpleasant

keen: have enthusiastic to do something.

lift: if you lift something, you move it to a higher position.

weight: used to point out how heaviness of something is.

quantum: the atomic activities 

loop: the round and circular shape about something.

corrections: the marks usually made on test book to tell where go wrong and what is the right answer.