noun
playing to the gallery; showing off; pretense
Refers to theatrical, exaggerated, or insincere behavior meant to impress an audience; often used in phrases like けれん味（み）のない (unpretentious, straightforward).
彼の演技にはけれんがない。
His performance is free of showing off.
あの政治家の演説はけれんが多すぎる。
That politician's speech has too much playing to the gallery.
The origin is uncertain; it may derive from a theatrical term, possibly related to 外連 (けれん) as a stage trick or gimmick. The kanji 外 (outside) and 連 (take along) are likely ateji.