Term that stands for "over the bridge." Used by Philadelphians to describe suburbanites and suburban attitudes, especially those associated with New Jersey. Similar to the usage of "bridge and tunnel" in New York, OTB originated because suburbanites from NJ have to cross one of several bridges over the Delaware River to get into the city. One does not necessarily have be from NJ to exhibit OTB characteristics. Many OTB people reside in Delco or Bucks County. Examples of OTB characteristics include loud and aggressive behavior, fist pumping, and enjoying chain restaurants.
Much to the chagrin of real Philadelphians, OTB people descend on the city every weekend, but they especially love the bars and clubs in Old City (possibly because they don't have to stray far from the bridge to reach them). When out of town the OTB people will say they're from Philly, but they've only actually ever hung out in Center City and maybe South Philly (but probably only near the stadiums) because they're afraid of the rest of the city.
"Dude, Eagles fans suck. They even booed Santa!"
"Come on man, don't judge our city based on those people. They're mostly OTB anyway."