This is quite funny request Ahahah.
So i think they r school boy n planning a trip to the beach with friends. The couple took the chance to play date n promised to wear the same swim trunk color (i think its pink). But on the d-day. Uke ended up wearing not so similar color to seme, so its quite a fail attempt. But actually uke wearing a sexy speedo underneath the swimtrunk. One of their friends found out about the uke and got real awkward. Ahahahha this happened when uke got his swim trunk swept away by the wave n everyone including seme panicked to find the lost swim trunk.
Sorry for my engljsh, i tried hard to expain the situations.
Raon is just the pervert