It's still a joke, which is why it does well. It's got a serious strain, but it's firmly rooted in internet sillyness and people throw it around willy-nilly right now specifically because it's a "joke" with some minimal amount of value. People treat it as functionally equivalent to reddit karma or whatever - at the moment, it's broadly used as kind of a secondary upvote. Just because it's a joke doesn't mean it can't also be a serious cryptocurrency. It's just rebranded Litecoin, after all.

As far as "second to bitcoin", not quite. Its market cap jumped quite a bit in the past day, but it's still 8th on the list according to http://coinmarketcap.com/