You can do a lot of things when there’s a 4-year-old in the room: You can juggle knives. You can teach the kid how to breathe fire using kerosene and a lighter. You can commit federal crimes and embezzle billions of dollars from unsuspecting companies. But what you can’t do — what you must NEVER do! — is let a scary scene from a scary movie flash on the TV or computer while that child is watching. Eyeballs will pop out. Hair will curl. And you’ll be explaining (and lying about) that scene for the next 12 or 13 years. Or at least until her lawyers have finished working you over. I learned this lesson the hard way the other night. We were at my brother’s house for a cookout, and my sister-in-law was explaining her Halloween costume. Only, there is no explaining her Halloween costume. It’s an obscure character from that quirky, spooky, goofy 80s flick, “Beetlejuice.” Seen it? Know who Delia Deetz is? Of course you don’t. Nobody does. My wife had never even seen “Beetlejuice,” so my sister-in-law thought she would show on the computer a scene from the flick.