A phrase with many meanings depending on the context it is used in and the inflection of the voice.

1. Agreeing with a comment and/or suggestion with great conviction.

2. Disagreeing with a comment and/or suggestion with great conviction.

3. The perfect rebuttal to any criticism, argument, logical debate, reasonable request or sexual advance.

4. (Adv.) Emphasizing the importance of an act.

Dejagoo is the strange feeling that you've been in this sticky situation before. It is dejavu due to goo. Usual symptoms are shivers down once's spine followed by disgust, especially if actual goo is involved.