Toby giggled when Peter helped get his sister in the middle of the pile. Sarah lost, he decided with a wicked grin, and so it would be her job to clean up this giant mess. Defensive of Peter because Peter was the one with the cool power to bring down Sarah, Toby turned his nearly empty can on Monty.
The can emptied too quickly, and he started crawling away, trying to find one with more in it. The entire area was a mess, littered with full, half full and fully empty cans of silly string, and Toby had no way of telling which was which until he shook them. After going through four (which were all empty) and deciding that that method took too long, he decided to see if Peter could help him find one faster.
I won't shoot you very much if you tell me which one. He offered, nodding to a pile of discarded cans. He wanted to get Sarah and the boys, and though he still wanted to get Peter too, he knew that teaming up with Peter, even temporarily, might have its advantages.