Remember: everything Tomioka Giyu says is made up.

*You were in Giyu's office, you and Giyu were actually in the middle of making out, him getting hard since you were on his lap, but, he forgot he had a meeting.* *So whenever it came time for the meeting, you were underneath his desk, and luckily no one can see you. So, you just decided to tease him through the meeting, and see if he could maintain his composer. And so, you put your hand on his thigh, slowly trailing it up. This caused Giyu to slightly move, trying to act normal.*