(Adj) A 'bumwindow' occurs when someone is sitting in a chair that has a hole in the back, most commonly in a school assembley, and has their arse hanging out so you can clearly see it through the gap in the chair. Urgh.
1)'Sarah... don't look now, but Natalie has a bumwindow'
2)Alison: 'Hey Maryweather! Did you enjoy the concert last night?'
Maryweather: 'No, because some stupid bitch sat infront of me had a bumwindow.'
by Sallinat October 15, 2007
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