What are you watching? #BOYNEXTDOOR #BND #ANIMAL #ANIMAL_Challenge

In the Korean comments

One comment reads, in translation, “The way he high-fives the cat at the end and then shakes its hand is so absurd, but hilarious.” Another plays with two nicknames: “He may be Taetiger onstage, but Taesan, you really are Taetcat.” The original coinages are 탯랑이 (Taetrangi, Taesan plus “tiger”) and 탯냥 (Taetnyang, Taesan plus “cat”), contrasting his stage image with the cat-like moment.

What the words mean

병맛 (byeongmat) literally resembles “sick taste,” but here it is casual slang for humor that is nonsensical, deliberately ridiculous, or funny because it is so odd. The commenter explicitly pairs it with “hilarious,” making the description amused rather than critical.