Well, with all due respect Kathi, if a guy told me I had a big bottom, no matter what he said before it or after it, it would not be received well. Now if he just said something like, "nice butt" or anything as long as he didn't make a reference to me being a BBW it would be good.
Maybe you are more comfortable in your skin than I am and my friends are, and comments of the like don't bother you. If this is the case, I bow my head to you in respect, you are more woman that I am, and I didn't mean that as a BBW pun either.
However, I do believe most women in my country would be offended by such a comment, and probably isn't the best advice for the poor lad in helping him with an effective pick-up line. It would most likely be ill received and cause the boy trouble. Next time just tell them to start singing that one song, "I like big butts and I cannot lie...", then if his message isn't well received he can at least gain his dignity back and recover slightly by saying something like, "oh Shreck, I love that movie, it cracks me up everytime." It's sly, but a good cover, lol.
Guys seriously, please don't tell a woman that they have a large anything, unless it's a smile. Trust me on this please. Good luck with the ladies friends.
Mashie