1) someone or something that just isnt right.
2) the feeling you get the morning after usuing a lot of drugs, most commonly associated with extacy.
3) something unsafe
4) someone or something that gives off a bad feeling

Iffy. Questionable.

creepy, iffy, fairly unsafe, an air of uncertainty, not kosher, and just generally something or someone that you don't want to be associated with (or really do want to be associated with, depending on who you are...)

This expression was first coined in reference to hastily drawn out, or sketched, building/construction plans, which were uncertain at best and disastrous at worst. The overall thread of meaning is the same, but now applies to morality/legality. On the overall continuim of goodness, things progress, in order: safe, sketchy, shady, outright criminal.

1. Adj. - Describes a person that has taken too much Speed and has become untrustworthy and unpredictable.

2. Also used to describe a place or action that is worrisome or unconfortable.

A really shady character, not one you would want to meet in a dark alleyway

Acting in a manner that is erratic, unpredictable, or untrustworthy; accompanied by paranoia, nervousness, and fidgeting - usually associated with meth users.