The phrase "slightest thing" means the smallest or tiniest occurrence or detail.
Sentences with «slightest thing»
Megamind gets existential, but only in blips, and while it is never anything less than vibrant and exceedingly clever, it is also a rather slight thing for such megasized proportions. (austinchronicle.com)
He lets them trust in the visual durability of physically slight things.» (artnews.com)
Fear that if you do the slightest thing wrong they will dump you. (inc.com)