The term originates from hackey-sack. A gravity check is when an easily playable sack hits the ground only because it was coming down equidistant between two or more players and each player didn't make an attempt because they thought someone else would play it.
The term can also be used in business to describe a situation where nobody on the team works on a task because they think someone else must already be working on it.
Your boss emails the whole team, "Gravitycheck. Earlier I sent an email to all of you asking that one of you please call the client today. Did any of you actually call the client?"
Cigarette: Northern slang for a cigarette, used oft by mashed up mancunian ravers becasue of the resemblance of a hot(electric)stove to the end of a lit cigarette. Originated circa 1991 in the early halcyon days of the rave culture; we speculate during a drug fuelled hallucination by said manc.
'fuck me noel, i am bolloxed, is that a ciggy in your mouth, or the stove from me 'nans kitchen'/
General use: 'Give us a stove you cunt'