Done as a Knee-Jerk Reaction
This page is the CodyCross answer for the clue below from Water Park, Group 759, Puzzle 1 (Hidden Grottos).
Question is: Done as a Knee-Jerk Reaction
and the answer is: ONIMPULSE
Word Meaning:
ON IMPULSE — Without prior consideration; spontaneously, impulsively.
Definitions from Wiktionary.