you can shit with the bathroom door open and your girl is in the next room...
you can let out a disturbing fart, and just giggle about it with eachother...
pretty much any type of bowel situation you can think of, and not be embarassed or disgusted when you are together...
when you can play XXX-rated strip poker and not be shy about being bucknaked infront of her performing sex acts on you when she loses the hand and vice versa.
when you show your lover all the imperfections you may have, to them, and consider it small talk...