In casual conversation, when you want to exaggerate an action or description, you use the adverb "totally". Here are some common examples of how "totally" is used:

I'm so sorry, I totally forgot to call you!

New Orleans was totally destroyed by the hurricane.

New York is totally different than it was back in the '80s.

Yes, I totally agree.

Evan's reaction was totally unexpected.

A slightly more formal word with a similar meaning is "completely". "Completely" could be used instead of "totally" in any of the examples above.