Cover your entire face in both liquid and powder blush, so that any natural blushing is disguised. She's not embarrassed, she's just insane

Beheading

Apply leaches to your cheeks. That should do it. 😉

Squeeze your own balls.

Repeat situations that make you blush. And go beyond those. Me: I did blush like a tomato when I have been kissed in public. But I loved that and repeated it as often as possible. Then I added a bit of hugging and bottom stroking to it. Which made me feel awkward a bit but I loved that too. After a while I stopped the bottom clapping and just indulged in kissing. Then that was not making me blush any more. Don't know if that works for you. Boys are different. Kissing boys in public seems to be more of a problem than girls usually depending on environment, but you get the principle?

Imagine everyone in their underwear! No wait, you said stop....imagine everyone in parkas?