Jim Jacobs and Warren Casey wrote "Greased Lightnin'" for Kenickie and the T-Birds to sing while they dream of fixing up his rundown car, but Danny (John Travolta) took the lead in the 1978 film at Travolta's request. The single was a much bigger hit in the UK, where it peaked at #11.
Jeff Conaway, who played Kenickie in the movie, injured his back during the sequence, leading to an addiction to painkillers that would follow him for the rest of his life.
In one shot, Travolta is shown rubbing plastic wrap over his crotch - a sly sexual reference to beat the censors. Back in the '50s, many misinformed teens tried to use Saran Wrap as a contraceptive when they were unable to buy condoms.
In high school productions (and in the 2016 Fox live adaptation), the lyrics are modified for young ears:
"The chicks will scream" (not "cream")
"She's a real dragon wagon" (not "pussy wagon")