It's been said that it's good luck when a bird poops on you. So how lucky are you if a plane accidentally lets loose on you?

A Long Island couple was enjoying a mild mid-winter evening last week when they felt black liquid fall on them as a plane was flying overhead after taking off from JFK airport, CBS Local reports.

Artie Hughes told 1010Wins: “Some black liquid, black oil came off on her [his wife's] face, and I walked around and I looked and said ‘Oh my God.’ There was quarter-sized, nickel-sized, dime-sized drops all over my deck, my barbecue, my table." (Click here to hear the report.)

Concerned, the couple called the police. The couple thought the mysterious substance was hydraulic fluid but a police officer who arrived at their house disagreed.

“He had spoken to somebody down at either the Port Authority or the FAA and said ‘Yeah, it looks like there was an incident',” Hughes said. “Some lavatory excrement had leaked out.”

A neighbor who stopped by couple's house shortly after the incident toldNewsday: "He said he and his wife were outside enjoying a couple of beverages on the deck and all of a sudden... they got pelted. As quick as it came, it left, and this happened right after a plane passed over."

FAA spokeswoman Kathleen Bergen told Newsday that an investigation would start Monday by taking a sample of the alleged poo. "This is very rare. More often we get reports of 'blue ice' falling in people's backyards"--which come from a plane's bathroom holding tank, she told the paper.

Gothamist.com talked with FAA spokesman Jim Peters, who told the site: "When this has happen[s], it's usually chemically treated waste that can sometimes leak out of the outer skin of the aircraft and clump up and break off. If it's that, we will try to determine what plane this occurred with."