Is mimicking someone lashon hara? If it’s something funny that happened can you mimic the situation and what that person said?
This depends on the circumstances, and on the intention of the mimicking.
Lashon Hara is a negative character trait, whereby a person hurts, speaks badly of, slanders etc. his fellow. If mimicking is done in this spirit, with intention of disparaging and insulting, it will fall under the category of Lashon Hara.
However, mimicking can also be “harmless fun,” without any hurtful intention or effect, and in this case there will not be any prohibition.