I've had a drink with 4 layers once where each liquid had a different density and colour. But alternating white/blue drink would look better than 4 different colours since it'd be harder to tell to tell the trick. Though that little bow decoration is a choking hazard.
In latin america there's a "drink" called "agua de calzón" (panties' drink), used by desperate woman to tie a desired man to them by mixing lots of (unsafe) things and the woman's underwear in water and making the victim drink it.
Anyone else notice Tanaka never reacts negatively to consuming bra related items? Once he found out that first drink was made with her bra, he started to rationalize the idea of drinking it. He was the same in the previous chapter, as well as the one with the underwear that purifies sweat into drinking water. He is always repulsed by panties, but not by bras.
I think Ueno's problem is that she always uses her panties in these inventions, and Tanaka's a boob man.