In Minecraft, there are a variety of blocks that are bouncy. The most common bouncy block is the slime block. Slime blocks are made from slime balls, which can be found in swamps. When you jump on a slime block, it will bounce you up high into the air.
Other bouncy blocks include sponge, honey blocks, and magma blocks. Sponge is found in oceans and can be used to absorb water. Honey blocks are made from honeycomb and can be found in bee nests. Magma blocks are found in the Nether and will damage players who stand on them.