what is the meaning of this sentence in an ironical atmosphere?

[dary]

Hi,

what is the meaning of this sentence at answering of an ironical sentence?

I had to look that one up.

Thank you.

[Mister Micawber]

.
I didn't understand it-- I had to look it up in my dictionary.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber

[dary]

Thank you so much Mister Micawber.