Get him a lid he can't pop through or wave goodbye. Many Oscars are career jumpers and will never stop. My own Oscar seems to see water dripping from the lid onto the surface, think it's a bug and lunge at it. But there are many things that could cause an Oscar to jump. Like a dog's face at 2:00 am.
All I do is put boulders onto the tank lids and seal the back with that plastic tracking that lids come with. So far, no jump-outs. Best of luck.
Are you sure there is no cause? Is your water healthy, tankmates suitable, etc.?