“Absolutely. Count me in!”
Your friend wants to rent a house at the beach for a group of friends to stay at. He asks if you'd like to come. You say yes.
Absolutely. Count me in!
Say "Absolutely" to express that you completely agree with what someone has said.
You can agree with someone's opinion this way.
A: I've always said that you shouldn't hire anyone who you don't feel 100% certain about.
B: Absolutely. I totally agree.
You can also agree to a request:
A: Hey, can I talk to you for a minute?
"Absolutely" sounds even more definite than "yes". You answer "Absolutely" when you're really sure that the answer is "yes".
When someone invites you to participate, you can say "yes" with the phrase "count me in":
A: I feel really good about this business opportunity so I was hoping that you'd be interested in investing.
B: Yeah, count me in.
Or you can speak for yourself and someone else, like your partner or friends:
If you guys ever decide to organize a camping trip, definitely count us in.