I can't stand the word ''mom'. I'm English born and raised, lived in the US for almost 50 years and always told my children (oldest 47 now) to call me mum not mom because I'm not American. "I'm British, so call me MUM", I'd say. As it turns out, while I wasn't watching you lot, you British mums started to call yourselves MOM. 
British words I can't stand anymore are fizzy drinks for pop, tummy instead of abdomen, womb instead of uterus, water infection instead of urinary tract (bladder) infection.
Americans have different regional accents, so words such as aunt are pronounced differently by region. Here they say 'don' instead of Dawn for example. It drives me up the wall.
I thought it was Sherman Tank = Yank.
Yanks (Yankees) are Americans who live in the North East. I think a southerner might be insulted to be called a Yank.
I've never use the word panties and have never heard anyone say it in real life here. We say underwear, drawers or britches in my neck of the wood - although I still say knickers.
Overall I still use the British words for things because you can take the girl out of England but you can't take England out of the girl.