I'm not an expert, but I've been around many, many children and all including my own, will "fake laugh" aloud at some point.  I'm sure you know adults that do the same thing.  I feel it to be an attention issue, they just want "to be heard".  Don't worry, as she matures, this will stop and remember, she's only 2 she may even be copying a friend or something she saw on tv, probably just a passing phase as they have many and to my experience, just when one phase passes another starts.  Just enjoy your daughter as she is because they grow and change so fast, this will be old news by summer.  Best wishes!