I have an American Internet buddy who is moving to Scotland. I know she checks out this blog sometimes so I thought I'd revive the word of the week, to help her learn some of the language before she goes.
To bagsie something is so claim it in advance. So you'd say "I bagsie first shot at the computer" or "bagsie the red pen".
In other words, I don't have my hand on the red pen yet, but don't touch it, I'm using it first, I've already bagsied it. There's really not an American equivalent to this word. It's unique and wonderful.
For reference, here are the previous word of the weeks: