The general idea of the sentence

[Dready]

Teachers, I can't understand what is said here. Can you please help out? No context, because it is taken from an exercise.

His hair couldn't be more violently on end, if it had been that moment dressed by the Cow with the crumpled horn in the house that Jack built.

 

[susiedqq]

Here's the reference to the Cow line:

"This is the house that Jack built..."
[FONT=Arial,Helvetica,Monaco]by Mother Goose[/FONT]

[FONT=Arial,Helvetica,Monaco]This is the house that Jack built.
This is the malt
That lay in the house that Jack built.
This is the rat,
That ate the malt
That lay in the house that Jack built.
This is the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the cow with the crumpled horn,
That tossed the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the maiden all forlorn,
That milked the cow with the crumpled horn,
That tossed the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the man all tattered and torn,
That kissed the maiden all forlorn,
That milked the cow with the crumpled horn,
That tossed the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the priest all shaven and shorn,
That married the man all tattered and torn,
That kissed the maiden all forlorn,
That milked the cow with the crumpled horn,
That tossed the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the cock that crowed in the morn,
That waked the priest all shaven and shorn,
That married the man all tattered and torn,
That kissed the maiden all forlorn,
That milked the cow with the crumpled horn,
That tossed the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.
This is the farmer sowing his corn,
That kept the cock that crowed in the morn,
That waked the priest all shaven and shorn,
That married the man all tattered and torn,
That kissed the maiden all forlorn,
That milked the cow with the crumpled horn,
That tossed the dog,
That worried the cat,
That killed the rat,
That ate the malt
That lay in the house that Jack built.

[/FONT]

 

[Raymott]

Teachers, I can't understand what is said here. Can you please help out? No context, because it is taken from an exercise.

His hair couldn't be more violently on end, if it had been that moment dressed by the Cow with the crumpled horn in the house that Jack built.

If someone's hair stands "on end", it means they've had a shock - like a cat goes when it's scared. 'Violently' means 'severely' here.
So, "His hair was violently on end"
Could it be more violently on end?
No, his hair couldn't be more violently on end - not even if it had been dressed ... Hair is "dressed" (combed , arranged) - that's what a hairdresser does.
"that moment" = 'then', at that time.
"dressed by the Cow ..." Here begins a silly bit. It doesn't really matter what that phrase is because his hair wouldn't be able to stand on end more violently no matter who dressed it.