Definition:
To be Socially engaged on online Social Networks into the wee hours of the night.

Meaning:
The incessant staying up not to miss out on all the social fun. Often caused by having a very lively online Social Network that is mostly located on the other side of the pond and the abundant availability of devices that make accessing ones social tools (Skype, Twitter, Facebook, etc) possible everywhere and anytime (eg. in bed). Doing it long enough could have detrimental consequences for sleep patterns and cause the subject to dream in ‘tweets’. (Though that could be seen as a good pre-Lotusphere training where sleep is hard to come by anyway).

Origin:
Derived from a combination of the word ‘Social‘ and the phrase “burning the Midnight Oil“: To work late into the night. Originally this was by the light of an oil lamp or candle but is nowadays replaced by the blueish shine of electronics and iShinies, hence the figurative terminology.

Related terms:
Insomniac, hermit, Twitter-critter