My friends said that I've become quite sarcastic nowadays.

Probably have to thank my friend Justin, who is the guru in sarcasm.

One thing that's really enjoyable when you do sarcasm is when you see the reaction from people - they could be speechless, maybe due to the fact that they know they are wrong or they have to agree with you because they were shocked... etc

Bottom line: Mild usage of sarcasm adds fun in conversation.