YEP, It's cum!

This reminds me of that one video about the cleanest milk in the world

Turns out it was'nt milk

She drank the whole mug, but in the 3rd panel it is full again

gans228 said:
She drank the whole mug, but in the 3rd panel it is full again

She went for a refill.

bubu1769 said:
She went for a refill.

Or just spat it back in the cup

This is a weirdly shmorky-ish comic.

I absolutely love the weird Sam and Max and Invader Zim vibes coming from this comic.

mcdonaldschicken15 said:
Or just spat it back in the cup

And then went for a refill

There actually is such a thing as literal horse milk, and also bull semen, so the same gag could be made with bulls, and she would be none the wiser if it was bull semen rather than cow milk given the right (or rather wrong) signage.

Honest mistake