Similar to the =_= face, =-= generally represents a squint-like glare accompianied by the pursing of the mouth; annoyance, indignance.
P1: Hey Bob, what's up?
P2: My room mate is listening to the Hamster Dance for the fifth time in a row. =-= It's all I can do to refrain from smashing his radio.
What is wrong with you? Why you you spent the time to write this? Is your school work to write an entire 10 page essay about your 1 inch dick? (plz don't get mad)
Person #1: Billy has never been the same since he got that weird ass teacher Person #2: Wdym?
Billy: `\]'/=[;.1qaz-pl,2wsx0okm3edc9ijn4rfv8uhb5tgb7ygv6yjm
Person #2 Damn, that's sad...