Why is it described at 'jumping in my grave' if someone jumps in your seat before you've barely got up?

Paula Meehan Dublin October 30th 2003
Would you Jump into My Grave as Quick?

Would you jump into my grave as quick?
my granny would ask when one of us took
her chair by the fire. You woman,
done up to the nines, red lips as a come on,
your breath reeking of drink
and your black eye on my man tonight
in a Dublin bar, think
first of the steep drop, the six dark feet

https://www.youtube.com/watch?v=qycR0FMZT3w

Is this a regional thing? I haven't heard it yet.

Hello Mrs Oliver Wood, y are you talking to yourself??????