Perhaps because it is a microwave and plugged in, the whole electrical hazard thing
Maybe it would be safer with a safe, unless it was a big one and tipped over and crushed you. Then it might not be such safe, safe sex in the first place
I thought the old saying was masturbating was like a microwave whereas sex is more like the oven. I think I might have misunderstood that.... So... Masturbate with a microwave and have sex with an over? Is that correct? Boy my life has been a lie all of these years!