I put an upgraded glue gunner and 3 un-upgraded ice monkeys, with them in a line and the glue gunner at the front. On round 47, a regrow rainbow balloon comes and I was able to use it such that the ice monkeys froze at nearly equal times apart from each other, somehow allowing it to stall forever with the glue gunner constantly shooting at the regrow rainbow.
Then I use a banana farm that gains passive income over time. And now, I have infinite money.