Slipped

He slipped on the wet steps and tumbled down the stairs.

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

She slipped on the rug and nearly fell down the stairs.

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

She slipped on the wet spot in the kitchen and dropped the dishes she was carrying.

He slipped a piece of paper into the envelope and sealed it shut.

The secret slipped out during the conversation, revealing the truth.

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