It's hard to explain exactly how this game came to be but the gist of it is that Ben and I were holding a blanket up between the couch and the blow-up mattress. E would jump off the blow-up mattress onto the blanket that would then collapse into a small pit.
He continued to do this all. evening. long.
Our blanket may have aged several years in one night but I think it was worth it because he definitely had a blast. Now I just need to be able to figure out more ways like this one to keep him entertained until we can start going to parks again!