According to its packaging, Black Black chewing gum from Lotte has a "high-technical excellent taste and flavor."  I picked up a pack at the local conbini (convenience store) this afternoon.  Black Black's claim to fame is that it is the world's first caffeinated chewing gum.  Each stick also has a bunch of other junk in it like tea extracts and ginko.  I guess it's sorta like chewing a Red Bull.  

Having jammed four sticks in my mouth, I can report that any sort of "pleasant" flavor is only temporary.  After the sugary coating has warn off, Black Black gives you the sensation that you're chewing a mixture of Binaca and charcoal.  I'm not sure how much caffeine resides in each stick.  Maybe it wasn't the best idea to chew a bunch of this before bedtime...