Pink-eye flight is a relatively¹ short flight that leaves late in the evening. A purple-eye flight is a flight that is taken or arrives at midnight. 

粉眼航班指夜间出发、航程相对较短的航班。紫眼航班则指午夜出发或到达的航班。

 

For example:

My flight to Sibu was delayed from 8:25 pm to 10:00 pm and then to 10:20 pm, just missing being a red eye flight by 1 hour and 41 minutes. I guess that makes it a pink eye flight.

我去诗巫的航班从晚上8:25延误到晚上10点，之后又延误到10:20，再差1小时41分钟就成红眼航班了。我估计我这个航班应该算粉眼航班了。