Should i get a long board or another bike?

Ive been working my butt off and ive been wondering if i should get a longboard which is cheaper then a mountain bike and also less flashier! I have a bike already (nice bike) but i was planning to get a new one but now im thinkng about trying something new and buying a longboard! They seem pretty neat,... what do yall think? What are the pros and the cons!