It is no secret that Katy Perry and Justin Bieber are very close friends.

This is why the sultry singer is always a special guest in Justin's epic parties.

And whenever there is a Justin Bieber party you can expect booze to flow endlessly. And if there is one female celebrity out there who likes to drink, it is Katy Perry.

There has been many instances where people have seen Katy Perry drunk at parties of Justin Bieber. In one party, Katy even was seen falling over in a nightclub after drinking one too many bottles.

It was reported that she stayed down for quite some time and it took two of her friends to get her back up again. That’s how drunk Katy was at the party. Katy wasn't seriously hurt though. In fact, she was seen partying again the following night.

When Katy and Justin party you can expect the festivities to last until the sun shines the next day. You're probably wondering what kind of alcoholic beverages are present in a Justin Bieber party.

At any party given by Bieber you can expect all sorts of alcoholic drinks such as champagne, vodka, tequila, different kinds of cocktails and many more. Bottles of Ciroc and Belvedere can also be seen in each table.

Even the most jaded of part-goer will find it hard not to get drunk at a Justin Bieber party. So no one can really blame Katy from getting totally wasted at a Justin Bieber party.

Katy Perry drunk at the party of Justin Bieber is really a common sight. It seems that every time the two pop idols are together, you can be sure that there will be partying and drinking involved.

Without a doubt, Katy Perry is one woman who really knows how to party.