The skill of removing as much ambiguity as possible is valuable. This includes ambiguity derived from loopy brain. Prepare to still be amazed by wild interpretations, but minimize what you can. One tip is to reduce message complexity and clearly separate concepts (in this case, the greeting and the actual instructions).
I get that, and I've had a reminder of an old failing at explicit communication to end users on my desk for 5+ years to help keep me grounded, but come on... In what interpretation other than Yoda giving instructions would an English as their first language user think 'hey hey!' was the username I was providing? It's out of frame, but the previous three sets of IMs I've sent this user started with hey hey! hey hey! and hello hello! so it's not like this was even a one off weird greeting for them (I should probably mix it up a bit more but what can you do)