When partners are not in the mood for sex but flirt and present sexual enthusiasm anyway. Secretly hoping to be rejected, avoiding the responsibility of pleasing their partner.
(Male)
When you are having protected sex and you go to pull out, but the tip of the condom sticks in the hole it was inserted in. As you continue to pull out the condom stretches between your dick and the hole, resembling the neck of a rubber chicken.
(Female)
A long chicken is when you are inserting something with a condom on it into an orifice (such as a vibrating egg or dildo) and you pull the item out in a way that stretches the condom between your hand and the orifice in question. The resulting stretched condom very closely resembling the neck of a rubber chicken.
"Oh man dude, I totally gave Sara a long chicken last night."
"... I was pulling the egg out but it slipped and I long chickened myself"