Replying to How do i convince my dad to let me get freestyle skis...

alright so hes probably gonna get me used salomon 2003-2004 pocket rockets for when we go on trips and stuff.. he thinks i can use it in the park also, but i want to go on rails and shit and i wouldn't wanna ruin them and there not even a true park ski...soo ive been buggin my dad to just let me buy a pair of freestyle skis that are affordable and hes being gay about it.. what should i do to convince him?