Screaming

My toddler is now at the stage where he frequently lets out a high-pitched shriek at any given moment. He’s excited or frustrated or mad at me or just wants attention. He doesn’t have behavioral issues (beyond being a normal toddler testing boundaries) or hearing problems. He has a listening problem. If I tell him to stop, he just looks at me and shrieks louder, like it’s a game. I’ll put him in time out after repeatedly telling him to stop, but it only works insofar as now he’s crying. And it seems like he’d be constantly in time out if I put him there every single time he did it. My MIL says to “pop” him in the mouth when he does it, but I hate that idea. Anyone with experience have any advice?