A proud segment of Igloo's slang series!
Appalachian/Southern Slang for getting bested in a road race, typically a car race.
Unlike getting your oil checked, this item of slang is perfectly innocent. It typically follows some desperately illegal driving.
The phrase has its origins in stock car racing. To improve the structural integrity of a standard production car for track racing, the mechanics would spot weld the doors shut. This strengthened the frame by making the doors a stiffening element of the frame. It also prevented the doors from flying open in a wreck, supposedly providing greater protection for the driver.
Of course, street racing is more accessible for a teenager, and with the almost mandatory illegality involved, street racing is also more attractive to a teenager. In addition to adding free-flow exhausts and performance carburetors, dudes began having their doors welded shut. This is why the Duke boys of the Dukes of Hazzard were always shown climbing in through the windows the General Lee, their 1968 Dodge Charger. In fact, allow me an aside here, these guys at my high school had the exact same make of car, with the General Lee paint job, and the Dixie horn. Yes, this is where I was raised. If I ever get into a "I grew up in the sticks" pissing match, I can usually trump with this.
However, the phrase was surprisingly left-handed in idiomatic usage:
Driver 1 and Driver 2 are in a race from Blacksburg, Virginia to Radford, Virginia. Both drivers proceed down Price's Fork Road at a high rate of speed. After completing a highly illegal pass across the double-yellow line into the oncoming lane, Driver 2 gets ahead of Driver 1. Driver 2 consolidates his lead, breaking ahead of an 18 wheeler. In fact, Driver 2 gets to Radford fast enough to be slurping on a chocolate shake in the Hardee's parking lot by the time Driver 1 pulls alongside.
Driver 2 (rolling down window): Hey there Johnny! (laying an appraising eye on Driver 1's car doors) Looks like you got your doors a little welded shut there?
Driver 1 (downcast): Yeah. They're welded on pretty good, you sonofabitch.
In accusing the losing driver, the winning driver chides the loser for his sin of pride. If a person literally takes the time and trouble to weld their doors shut, they must think they're pretty hot shit. And if there's something that folks can't stand in the mountains, it's self-importance and overweening pride. So, to tell someone that their doors are figuratively welded shut is to accuse them of false and unearned pride, poseurship.
Drive like you mean it, folks. And when you do race, do it to win, or your shit will get welded shut.