strange fetish revealed

so yeah my partner and i were doing the thing last night when suddenly out of nowhere they pull this weird old dildo out of their nightstand drawer. turns out its been a year now since they started secretly using it as part of foreplay, sliding it over parts of me during oral or when i’m naked or even in bed talking before we do stuff. kinda shocked themself at first but admit its turned into some major turn on for both of us. i mean there’s no real thrusting or anything just the idea and feel of it moving around close to where things are supposed to go. was wondering if anyone else has a weird fetish like this or if im overreacting by thinking we should stop because it makes me uncomfortable. what do u guys think?