Comment by PhasmaFelis

Google has five results for "giro shading" and four of them are this article, so I doubt that's a common name. It sounds like he's talking about untextured polygons with smoothing applied to hide the edges; the result tended to look like smooth, shiny plastic, without the usual sharp pixelation of low-res textures and low-poly models. It was definitely a common effect in the early '90s, though I mainly remember it from the N64, particularly Super Mario 64 and similar cartoony mascot games.

Edit: Kierenelby is right, he meant "gouraud shading". Here's an example: http://imgur.com/h8vNeaD It's pretty distinctive because a gouraud-shaded ball mostly looks like a sphere, but the outline is clearly polygonal, and the surface highlights follow the otherwise-hidden polygon edges in a weird way.