If you had a portal gun. What would you do with it.

Wouldn't you have to like... place a portal, mail them the gun, make sure they place the correct portal (perhaps wiring the box so it shoots when they open it), punch them, and then pull the gun back through the portal with you?

No, I would send a portal through the internet via ethernet port. It would end up on their screen, where I would then proceed to punch them.