Typically used in the phrase "before I punch a dolphin". Basically meaning; you are so fed up with something that you have little or no control over but you want control over you'd punch a magestic dolphin for it; either out of anger, compensation or to appall people in the figurative sense.
"I need to go on a tropical vacation soon before I punch a dolphin."
"This bars service needs to step up before I punch a dolphin in that place".
"One more hipster comment and I'm going to punch a dolphin in front of everybody."
An Australian term for masturbation
"Hey wazza I'm just gonna go out back and punch the dolphin"