The big O makes people say the craziest things. Maybe some people experience a disconnect with their brain when they put their foot in their mouths. Either that, or they're just plain weird for saying whatever it is they said that instantly killed the mood for you. How they can keep going is beyond me.
You can't exactly gag your partner (unless she's into that sort of thing--if she is, lucky you!) but you can let her know she says the darndest things when she's about to come by showing her this hilarious albeit awkward clip called How Not to Orgasm by Scott Rogowsky and Karley Sciortino.
It's especially awkward if she actually said some of this stuff. It might sound far out, but there are a lot of people who apparently can't handle all that pressure without going a little nuts. Enjoy!