2 definitions by SpenSpenni

A bone in occurs during intercourse between a male and a female, when the female has exercised her vaginal muscles to the extent that she is able to force her labia through the base of the male's crotch, absorbing a large portion of his pelvic region.

It can also occur during sex between two males, where the receiving male has exercised his anus enough to perform the act.

Scholars are still unsure whether this came before or after the bone out.
I love my girlfriend, but I'm afraid she may want to bone in.

If you're on the road to prison, it may be valuable for your well-being to master the technique of boning in.
by SpenSpenni January 17, 2011
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During sexual intercourse between a male and female, when the male is able to thrust his penis with enough velocity and just at the right angle to exit the female's body via the rectum.

A bone out can also occur in sex between two males. When the penis of the thrusting male is forced through the rectum and out of the urethra of the receiving male, a male on male bone out has occured.

Women and receiving males are also capable of achieving the rebuttal to a bone out, which is known as a bone in.
Dude, I don't understand why she didn't let me bone out. Obviously it's painful, but you have to respect those who are able to achieve a full BO...

Wow I got boned out in the prison shower... Yyyikes...
by SpenSpenni January 17, 2011
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