This one works, but unless you cinch her elbows uncomfortably tight (and this isn't good for her elbow joints, nerves and the circulation), then the elbow loops may slip downward. So it's good to add some rope yoke-like over the shoulders to stabilise this tie.
Otherwise it works quite well.

Addendum:
For those of you dedicated enough to surprise your girlfriend with this, here's a hint: The broomstick-tail is optional, you can do this by simply knotting the strands of cloth to the crotchrope.
So, use your common sense and your empathy: If she does not enjoy something in her butt (while bound or otherwise), don't scare her away by waving a lubricated 2x4 in front of her face. Use the PG-variant on her...