Taeyeon is a very slow texter, according to Key.
In the pre-recording interview for MBC Every1's 'Weekly Idol,' Key was asked to pick and text a friend that will reply to his message the fastest. He was also asked to guess what their response will be. Key picked Taeyeon and guessed that she'll reply, "Yeah?" in 20 minutes.
However, MC Kim Shin Young commented, "Taeyeon takes at least 5 hours to reply. There's no way she'll respond in 20 minutes."
Kim Shin Young was right. Taeyeon took 3 hours to respond. Key stated, "Now that I think about it, you're right. The phone bill is such a waste for Taeyeon noona. It only took 3 hours this time (though)."
In the end, Key sent a video message to Taeyeon, stating, "Taeyeon noona, I'm thankful that you at least responded but you should've replied 2 hours faster."