A person who thinks she or he's really something. A person who likes to show off. A person who believes she or he's bigger/better/cooler than the people around him/her. A delusion that you're much more powerful and influential than you really are. Also: overestimation of one's own capabilities.
Invented in Brixton, London, in February 2010. Expression taken from the name of an actual shop, i.e. Tile Giant, 140-142 Brixton Hill, London, SW2 1 RS, UK.
He thinks he's in charge of everything, I guess he thinks he's a tile giant!
He tells everyone (who doesn't want to know) how great his tricks are. He's a proper tile giant!
She thinks she can fly off that roof. Now she's a real tile giant!