Which is worse to have happen in front of coworkers and the big boss, loudly passing gas, or healthy belch?

If you are the newest kid in the office and want to make a good impression what would be the worse that could happen if you entered the big boss’s car to go across town with a few other workers to meet a client, rip off a big, loud, smelly fart, or a big loud belch? If you rip off a healthy fart do you just apologize to everyone open the window and pray they forget about it quick or is there something magical you can say? Do you say anything if you belch or do you keep quiet and see if they say anything equal to bless you or Gesundheit?