The Sneaky setting determines which side of the adjacent inventory the card attempts to operate on.
For example, a furnace accepts items from the 'Top Side' of the block. If the node is on a side of the furnace, set the sneaky mode of the insert card to 'Up'.
This card will now attempt to insert items into the 'top' side of the furnace.
Another card can be set to 'Sneaky Down' to insert fuel into the bottom of the furnace.