I just used the phrase bagsy in an email – then wondered if it was actually a real word. So Matt looked it up and…

bags

verb {T} (ALSO bagsy) UK CHILD’S WORD

to have the right to have or do something because you say you want it first:

– Bags I sit in the front seat! (= I said I wanted to do it first, so I should do it, not you.)

See also bag (OBTAIN).