The London Zoo is being investigated after allegations that drunken, lucrative after-hours parties are putting the animals' welfare in danger. Hammered, sometimes naked guests have repeatedly tried to enter animal enclosures, and in one case, "a beer [was] thrown over a tiger," the Guardian reports.

The Westminster city council began looking into the issue after zoo sources claimed that the ordinarily diligent zoo threw concerns about animals' safety "out of the window" during Zoo Lates events. A petition to stop the Friday night event series has collected more than 16,000 signatures.

The council will decide whether serving alcohol at the parties, which draw upward of 6,000 people a night, is such a good idea after a man stripped and tried to go swimming in the penguin pool and a drunk woman allegedly tried to break into the lion exhibit.

Zoo Lates is primarily attended by young, wealthy drinkers, the Guardian reported, and although music takes the form of a "silent disco," with guests listening via headphones, people constantly sing loudly while animals are trying to sleep.

"That's not what zoos are about, but there's a lot of money in it," a source told the Guardian. The events bring in around $1.35 million a year, according to the zoo.

The zoo countered that only three people have been ejected from Zoo Lates during the past two summers, but didn't specify whether those three were the penguin and lion enthusiasts and the tiger-soaker.

"We would ban alcohol if we thought it was necessary, but at the moment we see no need to do so," a spokeswoman said.

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