Dry ice is totally safe to put in your drink, as long as you don't actually ingest it. Basically, if you want to use it, make sure to allow it to stop smoking before drinking it. Dry ice also will not alter the taste of your drink, so don't worry! Just make sure to wait until all of the dry ice is evaporated before consuming. Seriously, this stuff is dangerously cold and it will burn you, your insides included!