"杯具 (bēi jù)", originally referring to a utensil containing water, has become an Internet buzzword as it is pronounced the same as "悲剧 (bēi jù, tragedy)".
Like the other popular Chinese character "囧 (jiǒng)", "杯具 (bēi jù)" is a versatile word in Chinese. The word "杯具 (bēi jù)" can be used to release one's frustration in an exam, love or work, or to express negative emotions in daily life. "杯具", which is written wrongly on purpose, seems to be less serious than the formal word "悲剧 (bēi jù)" (tragedy).
"杯具 (bēi jù)" can be used as an adjective or a noun. You can use it as an adjective in the sentences like "这太杯具了 (zhè tài bēi jù le, that's too tragic)" and "坐看杯具的发生 (zuò kàn bēi jù de fā shēng, waiting for the tragedy)". It can also be used as a verb, for example, you can say "你杯具了 (nǐ bēi jù le)" (Poor guy!).
Nowadays, many young people tend to use "杯具 (bēi jù)" instead of "悲剧 (bēi jù)" on the Internet or in daily life. "杯具" can be used to express one's unhappiness or show his/her dissatisfaction with someone in a polite way. In general, it's used in a joking way.
Like "杯具", many other similar homophonic words such as "洗具/喜剧 (xǐ jù, comedy)" and "餐具 (cān jù, 惨剧 (cǎn jù, tragedy or disaster)" have become popular among the young people online.
There is an argument saying people's overflowing negative emotions causes the popularity of "杯具 (bēi jù)". In fact, it's kind of a two-faced attitude towards life, self-mocking but positive, and these young people all believe in the saying "杯具会有的，洗具也会有的 (bēi jù huì yǒu de, xǐ jù yě huì yǒu de – Life is full of tragedies and happiness.)".