I don't know that there is a prescribed method of cleaning BBQ sauce out of a USB port. Note that if you don't get the sauce out, at minimum the port is likely to have issues. Worst case is shorting out the logic board. I suspect this is even more likely if you get liquid (Listerine) further inside the computer. There are repair places that specialize in spill cleanup. Certainly not cheap, but a lot less than a new logic board or MBP. If you're going to do anything more yourself, I would tilt the MBP straight up on its side, so the affected port is facing down, so any liquid will come out, not go in. I would have someone hold the MBP in this position and use dry cotton swabs to soak up as much as possible. Then I'd use rubbing alcohol to just barely moisten the tip of a cotton swab and see if any residue remains. If I was convinced that I had gotten everything out, I'd prop it up in this position and let it sit for 48 hours or more to completely dry. If you're lucky, you'll get all of it and the sugar and acid in the sauce won't corrode any circuitry.