A picture sent to a significant other that is living/ staying far away. Oftentimes this is in the case of girlfriends/wives of men in the Military. The pictures are normally slightly racy.
"Dude, my girlfriend sent me a moto pic of her in her underwear! And no you can’t see it, so don’t even ask.”
"I am sending my Marine a hot moto pic of me to remind him how much his girl loves and misses him while he is out fighting for our country.