Have you ever put your partners underwear on to masturbate

oh yes, very often.

Yes. Many times. my favourite way to jack off. And cum in them? Of course. It would be rude not to.

Have done it many times and wife will put on mine and masturbate.

Scooped up a pair of woman’s panties off the bathroom floor and was sniffing them when I came into bedroom. Started to lick the inside. Wife looks at me and says ‘Those aren’t mine. Those are my sister’s!’ (SIL was visiting and had just finished showering).