Spam

Spam is unneccisary quantities of useless bricks, projectiles, vehicles, chat messages, or other things intended to annoy or cause performance drops.

Spamming
Spamming, most notoriously done with red 1x1 bricks, is typically intended to annoy or cause lag on lower-end computers.

Spammy Building
Spammy building is building that resembles spam, using more bricks than what is neccisary. It's caused by overuse of small bricks when a a larger brick can be substituted to be just as functional. For example, a house made from 1x1x5 bricks scattered around the edge of a 16x16 plate would generally be considered a "spammy building".