Used to like hearing Jackson say if the player sees any daylight ahead of him in a seam opened up it will be Katy bar the door.
https://www.phrases.org.uk/meanings/katy-bar-the-door.html
The expression ‘Katy, bar the door’ means take precautions; there’s trouble ahead. The expresssion is also spelled as ‘Katie bar the door’ and the earliest example of the phrase in print spells it that way.
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The event was commemorated in Dante Gabriel Rossetti’s poem The King’s Tragedy, 1881. The full poem is 173 stanzas, but this selection shows the possible links with Katy bar the door:
Then the Queen cried, “Catherine, keep the door,
And I to this will suffice!”
At her word I rose all dazed to my feet,
And my heart was fire and ice.
…
Like iron felt my arm, as through
The staple I made it pass:-
Alack! it was flesh and bone - no more! 570
’Twas Catherine Douglas sprang to the door,
But I fell back Kate Barlass.
Which, if either, of the above explanations is correct is uncertain. The Kate Barlass story appears to have the stronger claim.