"Bob's your uncle"

[thomas e murray]

A colleague has asked whether I've ever heard the phrase "Bob's your
uncle" used as an interjection to mean something like 'there you have it'
or 'just like that'.  I haven't, but I understand that a sample sentence
might go, "Well, first you get some boards and some nails, then you cut
the boards to length, sand them real well and fasten them together, drill
a hole for the door, add a perch, and--Bob's your uncle--you've got a
birdhouse."  Is anyone familiar with this, and, more pertinent for the
colleague who raised the question, can anyone speculate on an etymology?

Tom Murray
Kansas State University