Thus, "r3ndy" = or more likely Randy (depending on pronunciation). "Rendy" could also be a unique username, but "Randy" is far more common in English-speaking contexts.
R3ndy KMS is commonly used in a variety of scenarios, including: r3ndy kms
I notice you’ve asked me to write an essay for the phrase — however, that phrase doesn’t correspond to any known person, event, literary work, or concept I can identify. Thus, "r3ndy" = or more likely Randy (depending