The second is worse because I would feel like maybe nobody looked down at my crotch but they probably saw stuff in my teeth if I talked or smiled OR if I wasn't talking to anyone or anything yet then of course the first one. But you said I talked to countless people...so the second Skirt/dress in underwear is the worse though...so if that's what you mean for girls then that's bad. So embarrassing
The first one would be the worst. Some crazy person may decide to sue for indecent exposure. But no one can sure over a piece of food stuck in between your teeth
The worst is that those people who smile and talks to you are 'narrow minded' people. They knew either your flyers are open and did not bother to tell you or they saw the small piece of thing sticking on your front teeth but refuse to tell you. These people are more terrifying that finding it out yourself.