Oops! Got the underlying myth premise precisely backwards!
And here they got the underlying business terms precisely backward. As an excuse for something like a missed payment, someone may plead that their assets are not liquid.
Okay, one joke is that there would be a rap version of a mantra. Or that she has been rapping it, or improvising it, or humming it or something, enough to disturb her friend.
But the bothersome aspect of this is how it seems to buy into some magical thinking. The dark-haired friend is linking her (later) ability to get the good parking space to performing a successful meditation now, undisturbed by intrusive mantra rapping. (Or could it be Nichiren Shōshū chanting?)
This is a perfectly fine little pun! Oh, except that there is no basis shown or hinted for why the new top provides more relief from the heat.