I found this gem while reading a Wikipedia entry for hornets.
It feels bad that I know some people who’d actually be dumb enough to try blowing hard into a nest entrance if they were told the wasps wouldn’t be able to come out then, specially if a bet would be involved.
Another action to avoid which is often confused with “breathing on a nest” is “breathing in the nest”, which, depending on the situation, and, depending on whether you’re a hornet or not, could result in worsened conditions of the breathee.