Slipped

The spy slipped the secret code into the message, without anyone realizing it.

He slipped on the oil spill in the garage and got his hands dirty.

The secret plan was slipped into a confidential memo, without anyone noticing.

He slipped on the wet pavement and sprained his ankle.

He slipped on the banana peel and landed on his backside.

She slipped on the icy sidewalk and slid several feet before coming to a stop.

The building's safety standards have slipped over the years due to lack of maintenance.

The spy slipped past the guard and entered the building undetected.

He slipped his backpack off his shoulder and onto the ground.