Stellar Types

So I've been living and breathing astronomy for four whole days now, and it's producing conversations like this:

ME: I've been observing the Wal-Mart parking lot, and I've noted twelve Class O supergiant vehicles, fifteen Class B giant vehicles, eight Class G vehicles, and nine Class M dwarf vehicles.

CARRIE: What conclusion do you derive from your observations?

ME: Big pickup trucks and Wal-Mart have a powerful mutual attraction.