Katy Perry‘s pre-taped ‘American Idolperformance (April 26) was interesting because of the military theme. But the singer’s voice was not at its best nor was it as thrilling as we’ve all seen her in the past, especially the previous times she’s torn through her new smash ‘Part of Me’ like a lion feasting on a gazelle. So why was her ‘Idol’ perf seemingly “off?”

Turns out that Perry was battling sickness and soldiered on like a trooper and like her military theme!

A source told Hollywood Life that Perry “was coughing up flem. It was a bit gross. She said she was trying to feel better from being sick.” It’s actually spelled “phlegm” and yeah, no matter how you spell it, it’s gross.

The taping was extended due to Perry not being 100 percent and the fact that one of the dancers fell while being lowered from the ceiling and smashed face first onto the floor. Perry sensed the audience’s restlessness, and offered to feed the crowd. “She said she was going to buy the audience Olive Garden, Jack in the Box and Cheesecake Factory for staying,” the insider shared. “It was a joke though and she didn’t go through on the promise.”

Seeing Katy Perry do her thing multiple times and working on getting her craft just right doesn’t seem like too stressful of an experience to us, so we wouldn’t need her to bribe us with good eats …even though she can afford it.

Watch Katy Perry Perform ‘Part of Me’ on ‘American Idol’