noun, na-adjective
big turnoff; major letdown; damper
Colloquial noun or adjectival noun describing a situation or remark that kills the mood, spoils the fun, or makes everyone lose interest. Often used when a joke falls flat or an event becomes awkward.
彼のつまらないギャグで場がどっちらけになった。
His lame joke made the whole atmosphere fall flat.
せっかくのパーティーが雨でどっちらけだ。
The party was a total letdown because of the rain.
Likely derived from the verb しらける (to lose interest) with an emphatic prefix どっ- and sound changes, giving a stronger colloquial feel. The exact derivation is uncertain.