This happened to me way back in 2003 - on a date with a rather nice guy. I was so nervous I swallowed funny and my food caught in my throat! I remember clearly my thought processes: "can't swallow, can't cough, can't breathe, can't talk - I have 4 and a half minutes until brain death unless someone in this restaurant knows the Heimlich. There are about 40 people here, I bet the odds are pretty good...and you know, my date's a handy guy, bet he might be one of them!" I stood up and started waving my hands around, forgot the "international sign for choking" (hands around the throat) but mimed the Heimlich and pointed at my mouth. My date figured it out, thankfully, did the Heimlich on me in front of 40 shocked onlookers, and saved my life! I found out 2 weeks later though that an acquaintance of mine had DIED in exactly the same circumstances because she had gone to the bathroom alone to try to clear her airway in private, and that this is a very common thing to happen. She literally died of embarrassment, of being too polite to make a fuss. Don't let this be you! If you're choking, get attention!

Oh and FWIW that rather nice guy and I have been married 16 years now :)

EDIT: IF YOU ARE ALONE AND CHOKING you can do the Heimlich maneuver on yourself! HERE is a very useful demo! Thank you to u/RanierMT for the link!