Urban Dictionary
prone bone
The sex position in which the [bottom] is laying flat (emphasis on laying completely flat) on [his] belly with penis entry from behind. This position often enables the [bottom] to work the muscles in the region resulting most likely in an overpleasurable time for the [top] involved, thus causing premature ejaculation.
I nailed [Linus] in prone bone last night!
Source: Urban Dictionary
prone bone
A sexual position where the [bottom] lays flat on [his] stomach with [his] legs together and the [top], on his knees, stradles [the bottom's] legs just below the butt, sitcking his penis into [the bottom's] now tightly-squeezed [manhole].
[Jeff] was napping face down in the nude when Rick climbed on and gave [him] the prone bone.
Source: Urban Dictionary