ROCK THE CASBAH. BtVS Intertext/Allusion.
In "The 'I' in Team" (Season Four), Spike refers to the track "Rock the Casbah" from The Clash’s 1982 LP Combat Rock when he and Giles are trying to figure out the device implanted in him by the Initiative which Xander correctly deduces is a tracer due to his ‘pseudo-soldier memory bank’ from "Halloween" (Season Two) when Ethan Rayne’s spell transformed him into a soldier.
Spike’s love of punk bands such as the Ramones (who he plays on stakeout in "Crush," Season Five) and the Sex Pistols (whose CDs he has in his crypt in "The Initiative," Season Four) is evidenced in various episodes and as Buffy notes in "Sleeper" (Season Seven), his look was the origin for Billy Idol’s bleached-haired style.
The following dialogue is taken from the Buffy Dialogue Database:
SPIKE: Oww! Watch it. That hurts.
GILES: It doesn't appear to be a bullet. It's too deeply embedded to be a tranquilizer dart.
SPIKE: (grumble) Also not tranquil.
GILES: Some sort of ... illumination emanating from it. It's blinking.
SPIKE: I don't care if it's playing 'Rockin' the Casbah' on the bloody Jew's harp, (growls) just get it out of me!
GILES: Anya, there's a bottle of cognac in the cabinet next to the sink. Can you get it for me?
SPIKE: What? You're gonna get snockered now?
GILES: It's not for me, you prat. If I'm gonna operate on you then I need you in anesthetized. It's going to take some time.
XANDER: We don't have any. That blinking thing. My pseudo-soldier memory bank tells me that's a tracer.
GILES: A what?
SPIKE: A what?
XANDER: It's like a homing beacon. And if commando guys are reading the signal, they're coming home.