All I did was call System.Diagnostics.Debugger.Break(). You’d think I’d tried to trigger the launch of a global thermonuclear war:
First, I get a few seconds of this:
Hey, Windows, I have an idea of how to solve the problem: launch a debugger!
But Windows has other ideas:

Luckily I noticed the previous ‘user defined breakpoint’ message, or at this point I’d have assumed that the program had just broken. Well, let’s click the ‘Debug’ button...

Woh – BIG dialog. Okay, let’s elevate the JIT debugger...
I can’t screengrab it, but now you must imagine the black curtain of death descending and an elevation prompt appearing.
FINALLY, we get the debugger launch prompt:

"Just-in-time" debugger? Too right it's 'just-in-time'. I was about to throw the computer out the window.
And, finally, just to put the icing on the cake, when VS finally gets hold of the process and goes to the appropriate stack frame, it presents me with this:

Ironically, of course, once I’ve dismissed this dialog I can actually load symbols for mscorlib, and then I do have source code for the current location.
That’s FIVE clicks to get into the debugger... FIVE!
Plus all the time I’ve lost writing this! Damn you, Microsoft! Whatever happened to 'Developers! Developers! Developers!'?