Inkling boys playing Splatoon as Inkling girl hitting on another Inkling girl it seems.
Guessing the joke here is that the ability "Echolocator" marks all enemies with that arrow around their body and draws line between you and them. Thus you can track their movement everywhere and through everything. Even when they are submerged.
So the linking here between two Inkling girls (ry :V
The story when I let my friend play that squid gameHey! Something appears! What's this!?