Let's clear out my "Butting" files with these offerings, which include some pratfalls as well.
First with her butt up is
Dixie Dugan. We might have seen this one before, but let's go ahead anyway. Dixie unwisely
bends over right in front of a billy goat:

From
Big Shot Comics #24
Then we have two pages of Bill Ward's
Torchy Todd, who doesn't exactly bend over but still gets it in the end and takes a pratfall as well. I don't know if the artwork here is by Ward or by Gil Fox:

From
Modern Comics #76
Then
Mopsy, whom we've seen twice recently, follows in Torchy's footsteps, getting butted by a bull and then taking a pratfall:

From
Mopsy #1
Then she goes skiing in the mountains and somehow winds up landing butt-first on a cactus plant in the desert. This one makes no sense to me, but here it is:

Also from
Mopsy #1
Then it's back to Harry Sahle's
Candy to see Candy and Ted's antagonist
Cornelia getting butted by another billy goat. Sahle's art never fails to disappoint, but at least we know Corny must have gotten it pretty good.

From
Police Comics #98
Lastly we have three pages of an exceptionally silly strip that was apparently called
Molly Muddle. Molly seems convinced she can fly, although the boys are doubtful, and to keep up the illusion that she can, her friend Taffy resorts to giving her a lot of pain where she sits down. First, she gets Molly to
bend over in front of a raging bull (just like Torchy and Mopsy):

Taffy induces Molly to
bend over, with predictable results. Molly says that "it hurts," the first reference to the butt-pain she gets in this sequence.
In the next scene, Molly re-creates the first scene, the most significant feature of which was that she was
bending over, which she does again in front of some reporters(!):

Molly
bends over once again, and this time Taffy sticks her with a pin, which somehow nobody sees. "I can't let her down, no matter how much it hurts!" Taffy thinks. Of course, it's not Taffy that it's going to hurt - what a pal! This is the second reference to Molly's butt-pain.
Finally, Molly and Taffy appear to have been hired to do an ice-skating routine, and they take (yes) -
a pratfall! 
At least this time Taffy is rubbing her own sore behind for once, but Molly has the last word in the final panel as she exclaims, "I neve want to sit down for the rest of my life!" This is the third reference to the pain in her rear end, which by now must be considerable, in this preposterous story. Couldn't poor Molly have just been paddled repeatedly? Not only would we have enjoyed it more, Molly's behind would probably have been less sore than after all this silliness.

From
Taffy #12