あんがい案外angai
1.

A feeling or realization that what actually occurs differs from one's initial expectations or commonly held beliefs.

2.

A situation or outcome that turns out to be contrary to what was anticipated, often leading to astonishment or a sense of disbelief.

3.

An instance when something goes better or differently than one might have reasonably guessed, leading to a sense of relief or unexpected pleasure.

Example:

ピクニックは案外つまらなかった。