If I accidentally freeze a soda can, I open the top with a can opener and have a slushee (clean cut). Any reason I couldn't keep the can and reuse as a cup?

I could have quite the fleet of cups going, but are there any risks? (Such as idk something degrading shrug) Any help much appreciated.

Example: http://i.imgur.com/rWb9R.jpg

As an aside, one of the google links I found was someone selling "2 for 5" soda can cups. lol