What illegal practice involves lending money at unreasonably high rates?

Forgery is incorrect because it involves falsely creating or altering a document with intent to deceive, such as signing someone else's name to a document. This has no direct relation to charging high interest rates on loans.

Altercation is incorrect because it refers to a verbal dispute or physical confrontation between parties, which is completely unrelated to lending practices or interest rates.

Puffing is incorrect because it refers to exaggerated or boastful statements about a property's value or features, which is a sales practice rather than a lending issue.