Definitely an Ultraman-based gag. I'll add the "color timer" tag, but I don't know if it's worth the copyright tag.

So apparently, she's using Ultraman Gaia's color timer ping.

CHAEU said:

So apparently, she's using Ultraman Gaia's color timer ping.

Or Zearth, specifically in the 2nd Ultraman Zearth movie, when Ultraman Shadow wipes him out at the start of the movie. Or even Tiga, in the direct-to-video special "Revival of the Ancient Giant". In which turn, Gaia's colour timer sounds are actually Tiga's colour timer sounds, but pitched a lil' higher.