Mocking 2 year old! Help!

For the past 5 days my 2 1/2 year old has been talking back a lot! He’s always been such a good kid. But the other day I told him no to opening the fridge (he was just opening it up for no reason) he yelled back at me no. It took me by surprise and I said excuse me? To which he said “excuuuseme!! No mommy!!! No!!!” At the top of his lungs and when I said “okay time out” which is in his crib he said “ no you timeout!” Where is this from?! And now every time I say anything he doesn’t agree with he repeats it back and tells. Today I told him it was time to come in since it started to really rain and he did the same thing THEN before I said anything he says “time out now!!!” And proceeded to put himself in time out. He waited about 3 minutes came out, said sorry only to yell at me again for the rain outside. What else can I do? I never yell at him. I always try to explain why we can’t do something but man this is out of left field! Help!