Celebrities galore took the stage with Andy Samberg's comedy pop trio The Lonely Island at Milwaukee's Summerfest Friday night.

Well, fake celebrities. There were Justin Timberlake and Lady Gaga — except they were actually puppets. And Michael Bolton made a "live" video screen appearance that clearly wasn't live. Green Bay Packers legend Brett Favre was there — except it actually was Lonely Island's Jorma Taccone wearing a wig and a No. 4 jersey.

T-Pain and Jose Canseco were there, too — as in, the real T-Pain and Jose Canseco.

Mr. Pain, who has a particular fondness for Wisconsin (or as he likes to pronounce it, Wiscansin), was serendipitously booked on the same night at Summerfest — on the stage right next to the stage the Lonely Island were playing.

So they got to perform their viral collaboration "I'm On a Boat" together at the end of the night for one of the largest crowds ever assembled at the festival's Miller Lite Oasis stage.

Fans were kind of expecting this — T-Pain's set ended early, and people were chanting "T-Pain, T-Pain," before he eventually took the stage to sing about relations with a mermaid through his signature Auto-Tune. (Warning: video clips are NSFW.)

But Canseco was quite a shock.

Netflix last month released the Lonely Island's "The Unauthorized Bash Brothers Experience," a ludicrous, "Lemonade"-style "visual poem" about that mocks Canseco and Mark McGwire's time with the Oakland Athletic's in the late 1980s.

During the show Friday, Samberg (as Canseco) and Akiva Schaffer (as McGwire) came out to do "Experience" anthem "Jose & Mark," but in the middle of the song, a towering Canseco showed up with a bat on his shoulder.

"Oh my god, he's going to kill us," Samberg screamed as he ran around the stage.

"I'm not going to kill you, I'm not even here to hurt you," Canseco said. "But you know what? You're doing this wrong. I'm going to show you how to do this the right way."

That prompted Canseco to lead a "They call me Jose" chant — with Schaffer dryly chiming in, "And I'm Mark."

Naturally, fans were thrilled about all of this — or upset about missing out.

But as fun as these real celebrity appearances were, we really enjoyed Taccone's fake Brett Favre, and the rap song he did.

"With the Green Bay Packers, I was a real MacGyver," he rapped. "I loved chucking the pig skin to Donald Driver."

He also rapped about butterburgers and cheese curds, because this is Wisconsin, and butterburgers and cheese curds are the best.

Summerfest 2019 lineup:The Lonely Island, Brandi Carlile and 131 other headliners

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