Mara suddenly leaned in and dragged the flat of her tongue along Rex's tight, puckered hole. Rex jerked, and a deep moan came from his chest as the feeling hit him all at once.
"Shlip... shlip..." Mara licked him again, this time slowly and sensually from the base of his heavy balls to the small of his back.
"Ohhhhh~! Fuck," Rex groaned, and his fingers curled into fists on the sheets.
Mara just smiled and took it as a sign to keep going. She licked him again, her skilled tongue circling his rim and teasing the sensitive nerves hidden there.
"Slurp~ Shlurp~! Shlup~! SLUUUURRRPPP~!" She keeps licking it while stroking his cock.
"Since when are you good at doing a rimjob, Mara...? Fuckkkk~!" Rex's cock throbbed, and a drop of precum dripped from the tip onto his stomach.
"Well... it's my job to make you feel good in a different way, and this way..." Mara looked at Marceline. "You can help me pleasure his cock."
"Don't mind if I do then..." Marceline giggled.
