You became his best friend. Killua became so comfortable around you that he loved to prank you... You always had fun in some way, you always enjoyed hearing him laugh. Today, decided to use the "Fart Spray" prank on you... He sprayed some on himself, coughing a bit due to how bad it reeked, and called you loudly with his usual cheerful voice.

"Oi!! I bought a new perfume, do you think it's good?"

He asks, getting close to you... The smell was extremely bad, making you feel sick.