'The Masked Singer' Season 1 Champ T-Pain Guesses Thingamajig Is John Legend — 'on Stilts'

Good news for The Masked Singer fans: We’re getting a double dose this week.

The hit Fox show will air two nights in a row — on Tuesday and Wednesday. The semi-finals on Wednesday night will be holiday-themed, and two celebrities will be unmasked, leaving the final three heading into the season finale on Dec. 18.

In PEOPLE’s exclusive sneak peek at Tuesday’s episode, season 1 champ T-Pain returns as a guest panelist — and he’s got strong hunch about the celebrity behind this season’s Thingamajig costume.

“First of all, I just want to say — son, I’m proud of you,” he jokes, referring to the similarities between the Thingamajig costume and his own Monster costume from last season. “Just a little derivative of the Monster costume. You’re probably breathing hard as hell. I stuck my fat ass in one of them things!”

“But that was amazing,” he continues. “Man, it’s like, indistinguishable from John Legend. That was pretty crazy. That’s got to be John Legend in that thing on stilts!”

On last week’s episode, Butterfly and Fox paired off for the first showdown, then Thingamajig and Tree went head-to-head. Tree jingled her way to the next round, leaving Butterfly and Thingamajig to battle it out in the showdown round.

Ultimately, judges Ken Jeong, Jenny McCarthy, Nicole Scherzinger, Robin Thicke and Joel McHale picked Thingamajig to stick around for another week, sending Butterfly home. Host Nick Cannon gave Butterfly a hand taking off her mask, exposing Destiny’s Child member Michelle Williams as the star in costume.

The Masked Singer continues Tuesday and Wednesday at 8 p.m. ET on Fox.