STAND YOUR GROUND, SISTER!!!! YOUR DAUGHTERS WILL THANK YOU FOR IT! At some point, they'll not want to be around their father because of his lack of maturity and disrespect. NOT the kind of male role model young girls need.
In addition, I'd tell the girls that THEY need to start speaking up, too. This is NOT being disrespectful. It's standing up for what is RIGHT and honors them and others. Otherwise, at that age, saying nothing is the same as approval. People who stand up for their beliefs and WHAT IS RIGHT stand a FAR LESS chance of getting disrespected and walked over by others and future boyfriends, etc.
Otherwise, they just think it's "normal" and take it! They need to TELLl their father that they need a role model who knows how to treat people with honor and respect (including you and them).