What's wrong with this thing?

Last night we went over to have dinner with our friends Marshal and Laverne. Zach and Isabella both polished off their milk pretty quickly and by the end of the meal were both asking for more. Lavern can't drink milk, so she offered soy milk. Liza filled both their cups with soy milk and handed them over. Isabella didn't really notice. She said it was like the milk she has at Nini's (my sister's) house. 

Zach, on the other hand, took a big drink, then pulled back and gave the cup a funny look. I thought, "uh oh, he's going to say no way." Then he took another big pull, and pulled it out again, and gave it a scowl. I wish I had a camera. It was almost like he was accusing the cup of something. But, not being deterred, he took another drink, followed by another scowl. By this time we were all laughing but he didn't notice. He was too busy trying to figure out what wrong with his milk right up until it was gone.