Spanish term (edited): "por las buenas o por las malas

"you'd better let me have it, or else"

eso diría yo.

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Note added at 19 minutos (2006-08-22 19:23:25 GMT)
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también:
"You'd better give it to me, or else."

Implying "but whatever happens, I'm getting the toy"

A possible alternative to "one way or another" that works nicely in this context of confrontation.

Spanish term (edited): por las buenas or por las malas

I like Marian's answer for the context but thought this would be an interesting contribution. My family uses it, anyway, so it's not totally obscure.

"by hook or by crook"
(Phrase Origins)

This phrase formerly meant "by fair means or foul", although now
it often (especially in the U.K.) means simply "by whatever
necessary means". The first recorded use is by John Wycliffe in
_Controversial Tracts_ (circa 1380). Theories include: a law or
custom in mediaeval England that allowed peasants to take as
firewood from the King's forests any deadwood that they could reach
with a shepherd's crook and cut off with a reaper's billhook;
rhyming words for "direct" (reachable with a long hook) and
"indirect" (roundabout); beginners' writing exercises, where letters
have hooks and brackets are "crooks"; and from "Hook" and "Crook",
the names of headlands on either side of a bay north of Waterford,
Ireland, referring to a captain's determination to make the haven of
the bay in bad weather using one headland or the other as a guide.

This phrase formerly meant "by fair means or foul", although now
it often (especially in the U.K.) means simply "by whatever
necessary means". The first recorded use is by John Wycliffe in
_Controversial Tracts_ (circa 1380). Theories include: a law or
custom in mediaeval England that allowed peasants to take as
firewood from the King's forests any deadwood that they could reach
with a shepherd's crook and cut off with a reaper's billhook;
rhyming words for "direct" (reachable with a long hook) and
"indirect" (roundabout); beginners' writing exercises, where letters
have hooks and brackets are "crooks"; and from "Hook" and "Crook",
the names of headlands on either side of a bay north of Waterford,
Ireland, referring to a captain's determination to make the haven of
the bay in bad weather using one headland or the other as a guide.

Hope it helps.

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Note added at 1 hr (2006-08-22 20:19:36 GMT)
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sorry, i didn't realize Heather Oland supported her answer with the same source!

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