sneakily

From sneaky +‎ -ly.

sneakily (comparative more sneakily, superlative most sneakily)

1. In a sneaky manner.
   • 1988, Tsitsi Dangarembga, Nervous Conditions, Faber & Faber Limited (2021), page 76:

     But on the occasions that he did do something actively nasty, he was satanically good at insinuating himself so sneakily into your most sensitive spots that if you did not know him well you could end up thinking you were being unfair to him when he annoyed you.