What does life have to do with a can of condensed milk??

WTF. My mum overreacted because I didn't know how to use a can opener. She mumbled about how the hell was I going to sail through life and stuff. -____- Beats me what life has to to do with cans. Geez. And she gave me the why-are-you-so-stupid face. Sigh. I get that alot.