For the Americans among us who may be sniggering: a rwber is a "rubber" in the sense of a little thing that rubs out pencil marks on paper: an eraser.
The word can also refer to the substance "rubber" that e.g. tyres are made of. (The name of that substance in English comes, I believe, from its use to rub out pencil marks.)
Rwber doesn't seem to be used for a condom in Welsh.