Do Females Know When You Are Staring At Their ?

Me and my friend were out with my mother and her friends at Red Lobster.We had a good time but he keep staring at my mothers friend Judy.He keep whispering to me that her were huge and that he could see her .I found that weird cause she like a mother to me.At the end of dinnerJudy looked disgusted.He does this on a regular basis.What im trying to ask is do they know your staring when your in a conversation or something like that.