Earliest place I found to do this was in the level Power of Love. At the beginning there are 3 glass structures you need Cyborg to destroy then build a Flash power build platform. Flash will create a water fountain that sprouts a couple bouncy flowers to go up to the next platform. Simply stay and bounce for a minute or so on one of them and the cheevo pops.
edit:
Another place that is relatively quick to get to is the Hall of Justice quest line, Nightwing's quest involves a lot of bouncy objects.
(For those not familiar with these Lego games, hold A to properly bounce on the bouncy objects.)