About "ways of speaking"

Hello,

I often read English speaker saying sentences like "I haz done it" instead of "I have...".

I guess it is like a speaking "joke", but I'd like to know if this comes from a particular place in the world or from a particular type of people ?

In the same way, I've heard "Where be'z you ?" and some other sentences using "be'z", like to replace every conjugated form of the verb "to be".

I'd like to know the same particulars of this kind of speaking type.

I've heard it in a video game, placed in the Middle-Age, "be's" may be a parody of Middle-Age peasants' way of speaking...

Thanks in advance,

Léo.

I put this question in this forum but it might be at the wrong place.

Sorry if it is the case.