If there is any reasonable doubt as to the ownership of the property or as to its liability to be taken on the execution the officer may require sufficient security to indemnify the officer for levying upon such property.
Wis. Stat. § 815.24
The term "reasonable" requires that the officer provide a reason for requiring security. Ter Maat v. Barnett, 156 Wis. 2d 737, 457 N.W.2d 551 (Ct. App. 1990).