Having a garadge sale today?

My mom and her boyfriend are having a garadge sale.. I volunteered to also sell some old cans of soda (I dont drink soda anymore and they arent expired either) and my mom just said "No". Im 12 and I really wanna make some money and just put some crystal light and water into a pitcher but they just laughed at me.. My sister who is 16 made me loose my confidence :( She made fun of me.. should I ask my mom again?