This is more fun than the time I got sucked into
the list of folk in line for the british crown!
"The Amazon River dolphin or boto has been reported to form up in bands of 3-5 individuals enjoying group sex. The groups usually comprise young males and sometimes one or two females. Sex is performed in non-reproductive ways, using snout, flippers and general rubbing, without regards to gender. They will sometimes perform homosexual penetration of the blowhole, the only known example of nasal sex. The males will sometimes also perform sex with tucuxi males, a small porpoise."
And there's more,
if you follow the links!