Dewlies is a word meaning "dual cans of Moutain Dew" - specifically one can in each hand. It is typically used by gamers and game developers who, without a steady stream of caffeine, would never be able to get as much done as they need to.
The term was created by game developers after a late night of staring at a computer monitor and constantly sipping Mountain Dew. The word is a play on the word "dualies", which is a Counter-Strike term for dual pistols.
Dewlies in hand, Blaine was ready to pull another all-nighter.