Do you use the 5 second rule?

No, but if I drop a piece of food for a very short time, I'm more likely to eat it than if it was down for a long time. 5 seconds is hardly a magic number, but it is true that bacteria take a little bit of time to move from one object to another.

You mean when waiting for the professor to show up before leaving?

If no one is around

Nope

I do

Not if it's ice cream.