I spoke of my real intentions unintentionally.
Koichi farted sooooo loudly that everybody reflexively covered their ears, but we should have covered our noses instead.
I saw the delicious looking picture and involuntarily started drooling.
This is the adverb version of the kanji think. You can't help but think, you do it unintentionally. So put this in front of things to say that you did them involuntarily.
The reading for this is the kun'yomi reading which you learned already, so you should be able to read this word as well.