I don't let him, much. The smarty-pants has found clever ways to swear without getting in trouble.
At the far end of the South Pier of the Duluth Ship Canal, on the wall of the lighthouse facing toward the lake (just a short bike ride from our house), is a wall laden with profanity. It's mostly from local kids out having a good time...a really good time from the looks of it. And Noah simply reads the lewd graffiti out loud, as if he's five years old again sounding out the words to Goodnight Moon.
"Mike & Candace 4Ever," pictured above, is the sweetest thing up there, and happens to be in the same frame as our house (one of the three little white bumps above the beach). The rest of the stuff on the wall is pretty graphic. So there's my sweet Noah, curious and innocent, sounding like a porn film.
Ask Noah or me sometime about the "free swear" on the Jay Cooke State Park hiking trails. You should have heard this child.