What would you do with a portal gun?

I can't say I wouldn't be curious to see what would happen to someone if they got shot with a portal gun, would the portal open and just suck them in or would the portal destroy them as it expands open, either ways what would you do with a portal gun? Id probably trap people I don't like in an endless loop where they just fall forever or until I shut off one of the portals, I'd also use it to look at the back of my head like a mirror, two portals on each side, when I look at one side portal I can see the back of my head through the other, id give myself a haircut πŸ’ˆ
What would you do with a portal gun?
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