With a bottle of lube

Brent reached over and picked up the bottle he entered the sauna with. He flipped the top up and squirted some of the clear gel onto his paw. He approached Samantha with a wry smirk and proceeded to nudge his fingertip against her sweet little tailhole. She gasped.
"Something wrong?" Brent inquired. He had thought the gel might be a little cold, not taking into account the fact that the sauna was hot and humid.
"Nothing. Keep going!" A sense of slight desperation in her voice. They had all stopped pleasuring each other over this little experiment of Karl's, and Samantha yearned for more.
Brent continued rubbing, with a gentle, sensual touch. He eventually introduced one finger in, and brought it up to the knuckle. Samantha fed him with encouragement, moaning and panting as he started to pump his finger in and out. He brought his first finger almost completely out, before slipping a second one in, and delving into her deep warmth. Stroking faster, and more rigorously, Brent eventually slipped a third and final finger in together. After a while, Samantha decided she was ready.
"OK, I'm happy. Come on and fuck me already!"