Not wasting the other person's time is however super-important, and a great fast test of whether someone is considerate enough to be an online friend or not.
This "play dumb" strategy worked great for me and I think it has less risk to be perceived as "rude" compared to sending a link to the nohello.com site.
Why do you have to wait for them to type out the real message? Is there some social/messaging etiquette that I'm breaking by ... read and get back to them when I have time?
hi - can you please approve this ticket 123
hi - URGENT the website is out can you please check the DB
hi - do you want to come to the bar tonight with the team
If you just say "hi", I dont know which one its going to be. Put it in one line I know whether to pay attention or do later.