When a girl "fucks" a potato. She inserts it into her vagina, and uses her cervix to suck it inside. The lips will slowly wrap around the potato, pulling it farther and farther inside.
John: I hear Melissa gets really lonely at night now that Tim is gone.
Steve: Yeah, I walked in on her giving a spudjob the other day.
When you have a mostly female orgy on Christmas.
John: So bro, what'd you do over the break?
Steve: I went to Julie's place and she had a couple more people over and we had a Pink Christmas.