Vegan ambassador chiming in:

I wonder what the mess from a water balloon full of e.g. Just Egg looks like.

Milkshake is piss-easy, though. Unless you’re in a bigger city, you’ll be lucky to find a proper milkshake purchasable in the wild. However, you can totally make one at home and put it in a disposable container; a homemade plant-based milkshake is about as hard as a homemade dairy-based one.

Wait is OP actually talking about throwing milkshakes at people, or is it a term for something else?

I of course have heard of the classic trope of egging people, but never heard of anyone “milkshaking” someone before. Im with you tho, I feel like milkshakes are too expensive and wasteful for this sorta thing, don’t wanna waste it all on a fascist!

Milkshaking is a real thing and does mean throwing milkshakes at people as a means of political protest.
Milkshaking - Wikipedia

Oh thanks for the info, TIL!