This is a reference to the game arras.io. Nexus is an event gamemode in Arras.io added on May 27th, 2023. It is the successor of the Dreadnoughts gamemode, but with many differences. This is currently the only event that stretches across multiple servers, regions, and even other gamemodes. However, Europe nexus server is a server mainly used for hanging out and e-sex (I'm not joking). Eu nexus can also be used as a verb, meaning to sex someone.
Person 1: Yo bro look at this, I cornered this poor machine gunner as a dreadnought.
Person 2: Eu nexus it.