Sagging - should I stop?

I just wanted to get public opinion on something which is affecting my relationship with my Mum and other members of my family. Since about year 8/9 (age 12-13), when I started a new school, I began sagging as I noticed lots of people doing it and it was a way to make new freinds and fit in. At first my Mum didn't really notice, but after a while when I began sagging more and more often, she began to always have a go at me about it. I'm in yr 13 now and i've been with my gf for about 18 months and she likes me sagging but my Mum and other people in my family don't really like it and it is affecting my relationship with them (particuarly my Mum). Given lots of other people in my school do the same and my gf likes it, should I stop just for my mum? - What's your opinion on sagging? Should I stop?