1Dropped by
a trophy, not a drop
Master mode is the only place these appear, and the eye is the earliest thing that can hand them over, so plenty of players end up wearing them before they own anything else worth showing off. In a group only one pair falls per kill no matter how many people were shooting, so if everybody wants them, plan on repeat summons.
whose sunglasses these are
They are named for a streamer who took the Moon Lord down on a hardcore character in expert mode. The tooltip is a joke about borrowing someone else's identity, the same gag the developer gear runs. They sit oddly among master mode loot because they carry the rarity color the streamer tribute items use rather than the one everything else from that difficulty gets.