... when you choke on your own SALIVA? Especially in the presence of other people!
There you are coughing away... eyes filling up with water... veins in your neck *and possibly forehead* poppin like a Justin Timberlake dance move... and everybody is crowding around thinking that your airway is blocked by some ill-mannered piece of food; you're thinking 'Lord I ain't ready to go yet!' In the crowd you can hear the shouts:
- Does anyone know the haemlich?
- Give her a hard clap on the back!
- Someone get a glass of water! *wtf?! I'm choking not dying of thirst!*

And then slowly the choking subsides and you regain your composure... and they're all waiting with bated breath to hear what exactly was the matter, as you sheepishly confess that 'twas your own saliva that doth offend you! The crowd parts and disperses with a groan of disappointment... and some upstart bellows:
"Is she own saliva she been ah choke pon? STUPEEESSSS! Ah tort she was deadin'!"
Yeah I'm glad to be alive too, you morbid wretch....