Everybody calls people these things all the time, without having ANY idea what they mean. As a public service, I thought this would be helpful.

Nebish

1. A person regarded as weak-willed or timid.
2. A person who is ineffectual, timid, and often luckless; a person of no significance.
3. One who is fearful and timid, especially in making decisions and plans, in discussions, debates, arguments, and confrontations, and in taking responsibility.

Nudnik

• noun An obtuse, boring, or bothersome person; a pest.

Schlemiel

1. A habitual bungler; a dolt.
2. A loser or a fool.
3. A person who is clumsy or who hurts others emotionally.

Schemazel

1. An extremely unlucky or inept person; a habitual failure.
2. A chronicallyunlucky
3. (Yiddish) a very unlucky or inept person who fails at everything