How do you keep a sleepy 4 year old awake in the van?

We were driving home from dinner with my dad and it was about 6:15pm and Monkey started nodding off. I kept waking him up but I was having a hard time keeping him awake. So J thought of the prefect way to wake him up and keep him up until we got home at 6:30pm. Out of the clear blue J puts his hands on his face and blows really hard making a super loud farting noise. That sure woke Monkey up! He did it again and I said, "Monkey, say excuse me." loud explosion of laughter throughout the van. Then the kids wanted to know how to make the noise themselves so we taught them on our way home. The kids even Red thought it was super funny and laughed the whole way home. I love those moments. And I'm sure their teachers appreciated their new found talent :) But hey they stayed awake and then went to sleep at the normal time so mission accomplished!