Fantastic Flail
From AmtWiki
An illegal flail which looks like a normal flail, but with an elastic or stretchy chain, (like Mr. Fantastic of the Fantastic Four).
One early notable example was used by Mithrandir at Clan in the mid 90s. While normally about 3 feet long, when stretched it reached over 6 feet.
Considered dangerous because of the possibility of the elastic chain wrapping around an arm or a knee and then pulling them out.
This type of weapon should not be allowed, and any flail should be checked for elasticity during weapon inspections.