I would try to implement gravity on them.
add an instance variable to the item you want to bounce called "vectorZ" (or something like that)
add an instance variable to the item you want to bounce called "bounces" set it to something like 3 (or however many bounces you want)
make a global variable called "Gravity" and set it to something under 0
in your event sheet:
for each {Bouncy Item}
{Bouncy Item}.vectorZ - Gravity
{Bouncy Item} Set Z elevation = self.ZElevation - self.vectorZ
(Sub event) Compare two values ({Bouncy Item}.ZElevation <= 0)
(Sub event) {Bouncy Item}.bounces > 0
{Bouncy Item} Set Z elevation = 0
{Bouncy Item} set vectorZ = 3
{Bouncy Item}.bounces - 1
else
{Bouncy Item} Set Z elevation = 0
This should make them bounce a couple times (I havent tested it.).