Andy Bernard graduated from Cornell "drunk half the time" to work at Dunder Mifflin Stanford. After meeting Jim Halpert for the first time and seeing him eat a tuna sandwich, he decided to call him "Big Tuna", and the nickname stuck ever since. In return for Andy's annoying tendencies (such as singing a capella), Jim put his stapler in Jell-o, but when Andy freaked out and kicked a garbage can across the room, Jim realized that he couldn't pull too many pranks on Andy without getting into a world of hurt.
The Stanford Branch eventually closed, and Andy 
was seen flipping out over it by throwing stuff in the kitchen. Once he transferred over to Scranton, he decided to suck up to boss Michael Scott and try and obtain the
coveted #2 position. While Andy did force Dwight to quit, he soon turned into a thorn in the side for Michael, with his constant offers of friendship. When Jim took Andy's cell phone, with its annoying ring tone of him
singing a capella, and threw it into the ceiling, Andy flipped out and punched a hole in the wall beside Michael's desk. Andy subsequently went into anger management, and returned to Dunder Mifflin a new man, no longer
power hungry, but rather, with a bunch of new techniques for "dealing with the grumpies". Dwight was still mad at Andy for what he did, and decided to shun Andy for 3 years; however, in a few weeks time, they had become friends.
Andy eventually focused on finding a girl at work, as he was rather starved for 
female companionship (after breaking up
with his girlfriend, who told Andy she was a "frozen yogurt chef" but in reality, was a high school student... although he didn't do anything illegal with
her). He did go for Pam (Jim's idea), but that didn't work, because Jim told him to do everything Pam hates. He pursued and eventually won over Angela, and they recently got engaged. Andy is