Doctor: I have some bad news and some very bad news.
Patient: Well, you might as well give me the bad news first.
Doctor: The lab called with your test results. They said you have 24 hours to live.
Patient: 24 hours! That's terrible!! What could be worse? What's the very bad news?
Doctor: I've been trying to reach you since yesterday.
A lab is short for a laboratory
To reach someone means to contact them.
You might/may as well means It means the same to me if you do or don't.
"Do you want to clean the living room or the bathroom?"
"I don't mind."
"Well, in that case, you might as well do the bathroom."