The term lolzer was created as an alternative to the internet term "lol" meaning laugh out loud which is now considered overused by many people.
Lolzer can be used to acknowledge amusement at an object or an event in the same way as lol. It can be written, typed but is most popularly used in everyday spoken conversation.
It can also be used in a descriptive context.
e.g, when something funny happens one would exclaim "Thats a lolzer!"
In contrast when something that unamusing or serious happens it would be said that "That is not a lolzer"
Jim: "I was just reaching over to close the window and I tripped and face-planted on the windowsill."
Bob: "Thats a lolzer!"
Jim: "I think I might have broken my nose, it hurts pretty bad."
Bob: "Ah, ok. That is not a lolzer."
Kim: "My mum just phoned the house to ask me where I was?!"