The Groovy Whip is a weapon in Ninjago, primarily associated with Skulkin General Wyplash. Apparently, it is a whip made from the dangerous Groovy Vine plant, making it inescapable if it successfully catches a victim.
Ninjago.com Description
The wild Groovy Vine is one of the most dangerous plants in Ninjago, because once it grabs you, it'll never let go. This whip is from that plant, so be careful or be caught.