Are family members allowed to blow an airhorn for their loved one at their graduation ceremony?

I find it inappropriate. It is rude.
Others do it, but that doesn't make it right.
The problem is that it usually interrupts the next kid's name. How would you feel if you didn't get to hear your kid's name announced?

Yeah - because all those in attendance should pay attention to [b][i]you[/i][/b] - instead of the graduates.

Why not go for the topless airhorn?

Don't do that, please God.

A graduation is a meaningful accomplishment that should not be made like a sporting event you bring graduation down to the level of scoring a three pointer. It is considered rude and found upon.

No, only at funeral.

The first person to do so will probably get away with it. Not so likely for others.