Ricky was dumbed-down.
The original Ricky from the first pilot and skits before the real Trailer Park Boys began it showed that Ricky was a very reasonable person and not really that moronic of a guy as he is now. Granted, I guess they needed one of the three boys to be shíts for brains so Ricky got picked.
I still love Ricky's character but there are a few jokes that fall flat and feel really forced, as is the case with "I toad a so" - https://www.youtube.com/watch?v=bhFHIlwCSq0 To be honest, I don't remember laughing/chuckling at this joke too often maybe once or twice.