Because women aren't allowed to.
I was inadvertantly sexist yesterday.
I visited the dentist's to have a filling replaced. An extremely attractive young dental assistant showed me into the surgery. It turned out she wasn't the dental assistant; she was the dentist.
I'm not particularly good with needles, and flinched as she was injecting my gum. Half of the anaesthetic ended up in my mouth. It was disgusting.
After a while, she asked if my tongue and lips had started to go numb. They hadn't. We gave it a few more minutes. Still nothing.
"Would you like me to give you some more anaesthetic?" she asked. "We did lose quite a bit."
"No, I'll be fine," I said, bravely.
I'm pretty sure I'd have said yes please, if she'd been a bloke.