[monday]

Sarcasm doesn't translate well in writing. It depends on tone of voice as well as facial expression. Deadpan tone with a roll of the eyes is a sure sign of sarcasm.

In reading what someone has written it's best to take what is written at face value unless someone uses the /<sarcasm tag. It is why it was invented and it's use means you don't have to have the ability to read someones mind to know what their intentions are.

[Rennes Templar]

Beginning a sentence with “Yeah” and ending with “hehe” certainly would lend one toward a literary interpretation of sarcasm, or at least a tone of non-seriousness.