1. "Elephant in the room" is an English metaphorical idiom for an obvious truth that is either being ignored or going unaddressed. The idiomatic expression also applies to an obvious problem or risk no one wants to discuss.
2. "Seeing pink elephants" is a euphemism for drunken hallucination, caused by alcoholic hallucinosis or delirium tremens.
<em>NB</em> Pink elephants do exist in nature, as it is possible for albino elephants to be pink, as well as white.
Thanks, Neil. It's interesting to know.
It appears that elephant idioms come in both pink and white!
"white elephant" http://idioms.thefreedictionary.com/Elephants
something that is large and unwieldy and is either a nuisance or expensive to keep up: "Bob's father-in-law has given him an old Rolls Royce, but it's a real white elephant. He has no place to park it and can't afford the gas for it." "Those antique vases Aunt Mary gave me are white elephants. They're ugly and I have no place to put them." "The town's new leisure centre, recently completed at a cost of ten million pounds, seems likely to prove a white elephant."