The word Sus is meant to suggest that someone is believed to be Shady or False. They are hiding something or are believed to have a serious character flaw. Which makes them undesirible as a friend or acqaintence. And/or straight stupid. A sus person can be any on of the following - gay, a snitch, a trick, annoying, weird, retarted, stinky, thirsty, fat, short, old looking but actually young, a social loser, a tag along, a friend that you are ashamed of, a mexican, pretty much anything that has a derogatory meaning to it can be put under the sus category.
You hear that song that Drake made for that girl?
Yeah bro that was sus as fuck