Assume the position

[Becky]

prepare to be physically humiliated
a command given during fraternity initiations, military [hazing], or [B/D](which are really not that different) to the [pledge]/[plebe]/[gimp]

[Couch Potatoe]

assume the position: To tell someone to get down on all fours (hands and knees) preferably when they are naked. The person who is being told assumes they will be receiving something soon.

[Couch Potatoe]

It could be viewed and used sexually... but in reality..
It is a statement that you make right before you make a big assumption. Im not quite sure on the technicalities of it all but...
Assume (v)
6. To take for granted; suppose
Position (N)
6.A point of view or attitude on a certain question
So you are taking for granted, or supposing, on a point of view or attitude on a given subject.
If you say this around your friends, they will think of the nasty word first, but then you can impress them with your superior vocabulary skills.
This was possibly made popular from HBOs Robert Wuhl Assume the Position. Where he talks about things that history books tend to ignore.