It's one of those American things. A pickup truck has what is called a tailgate. It's a panel at the very end of the pickup truck bed. It folds down and can be used as a table - or a seat. Before a lot of sporting events (American football especially) fans have taken to getting to the Stadium early and eating in the parking lot - and drinking before the game. Some people bring lots of food and grill or barbeque out. It's really a social thing - it's been going on since the seventies. Well - at some point concert goers picked up the habit for stadium shows too. So it's a time to meet before the concert in the parking lot and hang out with friends and eat and drink. Especially at concerts - there is lots of music being boomed from cars - usually the act that is playing that day. It can be a lot of fun - and in bad weather it can be really awful LOL.

Kathleen