Whale of A Timeって何?

From Twitter:
1. A. _ animal do ya think is _ smartest?
2. B. _ Blue whale.
3. A. _ whale?
B. It’s been here millions of years.
A. ?
4. B. It’s the largest mammal, with _ brain _ size of _ car.
A. That makes it smartest?
B. Its behavior, brain size…. It’s likely; we just can’t talk.

*the
*a
*what

Information: Blue whales are actually the largest known beings to have lived on the planet. A Blue Whale can grow to 90 feet long and is larger than the largest dinosaurs. Pink whales cannot. In fact, Blue whales do not allow pin whales to join in any Blue whale games. No, that’s not true; I’m just kidding. They do. I mean there is no such thing as a pink whale (unless of course a blue whale goes to a costume party or something. No. I’m joking. There are no costume parties for whales. They keep a strict dress code. A Blue can weigh as much as 130 tons. Imagine maintaining that diet!

Answers And Explanation:
1. what; self-explanatory: ‘what’ is the question word for things in question.
2. the
3. the
4. the, the, the
The is article is necessary to use in discussions of an object or abstract thing in general terms.