I take bars to work and also a lidded plastic tumbler I got from matalan for £1.50, which I find great. I take this everywhere with me, days out etc as its much smaller that the sports cup- shaker I got online. Usually put water and a handful of ice in it, then when I bung in the powder later on, it's still nice and chilled.
I also make the vanilla and choc ones hot with coffee. In the early days at work if anyone asked I just said it was a latte or hot choc sachet. X