Yoona: I can’t really participate in the lessons at the office very much. So, I’ll tell you in the future. My favorite Japanese is “Doki doki” and “Arigatou gozaimasu”. (Note: “Doki Doki” is the sound of your heart beating and “arigatou gozaimasu” means “Thank you.”)
Oh, YoonA likes a Japanese word "doki doki"

The girls' songs often use *onomatopoeia* in the most effective way in their lyrics.
You guys all know;
Girls: Doogeun Doogeun Doogeun Doogeun
YoonA: Doogeun Doogeun georyeo bameh jamdo mot eerujyo
(from "Gee")
They often use a Korean onomatopoeia "doogeun doogeun" just as in "Gee" above.
The Japanese onomatopoeia "doki doki" has exactly the same meaning and usage as "doogeun doogeun".
So YoonA can sing Gee as;
Girls: doki doki doki doki
YoonA: doki doki georyeo bameh jamdo mot eerujyo
when they are in Japan.
