I'm 19, and can wear tight jeans without flabby overhangs etc. I'm actually addicted to the feel of new non-stretch jeans, which means that when I can afford it, I buy a brand new pair.
As long as I'm not doing any gymnastics like toe-touching, I really like the tight all over feeling.
On the right body, jeans make your backside, thighs and 'frontside' look great.
I hope I can wear them until nature (old age or pregnancy) intervenes!