Ben 10 season 4 episode 4 : Big Fat Alien Wedding

Ben, Gwen, and Grandpa Max attend a family wedding for Max's nephew Joel and his bride-to-be, Camille. Before the day of the wedding, Ben tries to go swimming in the lake, only to interrupt a mud alien's attempt to sabotage the wedding. Ben defeats the sludge alien as Cannonbolt, but finds the groom's parents pointing rifles at him soon after. He escapes with Gwen's help, and Max explains that the groom's side of the family are all Plumbers, while the bride's side are all mud-like aliens, called "Sludges", which the Plumbers were enemies with until Joel and Camille meet. This wedding represents a truce. During a dinner time with the families, they were confronted by Camille's ex-boyfriend. Ben tries fighting him with Diamondhead, but realises the Sludge is immuned to the diamond ammunition. As they fought, Diamondhead pushes Camille's ex-boyfriend into a hot tub, where he dissolved into the water. After the incident, Joel's parents tried to convince Joel and Camille to cancel the wedding. They refused, forbidding them to brind any Plumber gear and the wedding continued the next day. However, on the wedding day, chaos erupts when Camille's parents and ex-boyfriend revolt against the marriage. Max realises that they just set up the ex-boyfriend plot, so they could hide their own true colours. The opposition showed their true selves and attempt to eradicate Joel. As Heatblast, Ben defeats them with a little help from Max, who bought some Plumber weapons, and the angry bride.