This is a mug shaped like an upside down pineapple with a feminine Tiki Bob style face. The name is a knowing nod to the (possibly urban legend) use of upside down pineapples to signify that someone is a "swinger" and indulges in casual sex parties.

From Eekum Bookum:

"I’ll be releasing my upside-down pineapple Bob inspired mug that I named 'The Swinger' next Saturday 25 June in Palm Springs Ca. It’s the weekend of Mucho Caliente and Rory has me scheduled for 5 pm right before yacht rock. I’ll have 50 of these beauties with me for that weekend."