NO LOITERING!

Well, with you and Bob standing around in the first room there's a chance of a pile-up. You two need to
move on....so here's how to crash 3.

I put a barrel on the green button, another in the green gate, then take the one off the green button. Then I push that onto the yellow button, go down and push the lower one left, then go back to the right, up and around and push it straight down (and stand still until the other 4 barrels come out).
I'm sure it can be done lots of ways, but that was easiest for me.