A classic Japanese phrase! "ドッコイ" (dokkoi) is a term used to express disappointment or frustration, similar to saying "oh no!" or "what a shame!" in English. It's often accompanied by a shrugging motion with the shoulders.

For example, if someone doesn't get their favorite food at a restaurant, they might say "ドッコイ" (dokkoi) and shake their head.

There are many variations of this phrase, such as:

* ドッコイな ("Dokkoi na") - This is a more polite version, used when expressing disappointment without being too strong.
* ドッコイじゃねー ("Dokkoi ja nee") - This means "it's really frustrating" or "what a shame!"
* ドッコイやない ("Dokkoi ya nai") - This is a more casual way of saying "oh no!" or "what a pity!"

I hope this helps you understand the nuances of this fun phrase!