"Sir, your dog sat on my feet."
Translation:Monsieur, votre chien s'est assis sur mes pieds.
Although grammatically correct, the combination "Monsieur, ton ..." sounds extremely odd. Basically, combining a form of respect or formality (e.g. the use of Monsieur) with a form of colloquialism or informality (e.g. the use of the tu form) doesn't sound natural.
It is present in some cases: (i) among non-native speakers, but that can be seen as the influence of their native language in French (ii) when one wants to express sarcasm/irony in order to show that one does not want to show the due respect they should (imagine saying for instance "Would you mind shut the **** up, please?") (iii) among people in state of intoxication (e.g. people under the influence of some medication)