i just sneak away and say something like 'im going to the bathroom' while hiding the stain behind my arm

I clean it with my finger when it's food. When it's paint, just leave it that way.

Say "Damn, it's my favourite shirt."
Then carry on eating.

I start screaming , and shouting 'SOS, SOS EMERGENCY, BEEEEEEEP BEEEEEEEEEEP' and tell everyone to call 911.

cry and cry.