Someone with a massive head. Named after the first satellite in space due to the fact it l, too, was both massive and spherical.
"Hey dude, I saw Jake todya"
"Who, Jake Sputnik head?"
"Who's Jake Sputnik head?"
"The one with the large, spherical head."
A polite way to call someone a chav.
"Hey! She's not a Thot, she's just chavically challenged"