I have two avid jumpers (and will probably have a third in DS3). We discourage jumping on the couch because they will ultimately ruin our couches if they keep it up. Same goes for the beds. Springs will only last so long when two 20kg kids start their trampoline act! They have a trampoline outside and we shoo them out.

When DS1 turned 2 we brought him a mini trampoline that had a handlebar across it. Both he, and then DS2 loved it. And it did seem to deter the couch jumping. Unfortunately it broke due to wear and tear ... and that's when we moved up to the big trampoline for outside.

Just as an aside ... both my older boys have some sensory processing issues (DS2 far more than DS1), but it means they actively seek out "bashing and crashing" - so couch jumping, both on it and off it onto things - as a way of sensory gratification, if that makes sense. It helps them "tick". And I'm definitely not suggesting that any kid who couch jumps has sensory issues - most probably don't - but in our household we've come to understand that it can mean a bit more than just having a good old jump for the heck of it.