For "Look at this" he will say "'ook at hiss!"
If I pull him up on it - he will make a half hearted effort to correct himself, but really doesn't have the patience .. he will say "Viss" for "This" ... and he IS capable that articulating the "Th" sound.
His whole method of speech is, and always has been, slurry and indistinct. His speech didn't develop normally or until very late. He has had speech therapy to 'find' all his sounds, but although he now is capable of making them all, he doesn't use them in conversation, especially not if very excited (which is normally)
How can I get him to clarify his speech? I don't want to be on his back all the time, but on the other hand it is laziness, not an inability, and he is very difficult to understand sometimes. (and he doesn't care)