Opun "Black Hole" Mcgrrrr was the son of Hethra Mcgrrrr, the founder of the Black Hole Pirates. He was also the former owner of the Holiday Towers hotel on Cloud City, though Jabba Desilijic Tiure later took control.
In 0 BBY, as a revenge for Jabba's coup for the Holiday Towers, he stole the droid CZ-3 while staying as a guest at Jabba's town house in Mos Eisley. His intentions were to take revenge on Jabba by gaining access to the secrets hidden in the droid. However, Jabba had foreseen this eventuality and CZ-3 was spying Mcgrrrr. The entire operation turned out to be a sting operation set up by Jabba anyway.
This plan was foiled because the Jawa Aguilae and her partner, the Squib Macemillian-winduarté, stole the droid from him (or, as they would claim, found or bought it after it malfunctioned and went wild.) Mcgrrrr, infuriated, sent his Jenet henchman Tols Vengra after the droid.
Vengra found the droid at the same time as Jabba's bounty hunter Takeel did. While they were arguing, Takeel's brother Zutton shot and destroyed the droid. However, in the process, CZ-3 had provided Jabba with enough evidence to expose Mcgrrrr and Vengra's plots against Jabba. Jabba presumably dealt with Mgrrrr and Vengra in his usual manner.