I was with one of my regular partners. The N-S pair, whom I hadn't met before, never actually explained what (non-Acol) system they were playing (most of our club play Acol, and most of us don't show CCs), but they were alerting all their low-level bids, and I think they were playing Precision. Anyway, South explained the redouble as 3+ support for hearts.
Obviously we couldn't leave them in 1♥xx, but was it my partner's duty to take us out? My view is, no: hers is a 'free bid' and therefore if she has nothing to show she should leave it to me: after all I have shown some strength.
What happened was that she bid 1♠ as a sort of 'SOS'; I naturally interpreted this as showing a spade suit and some values, so I raised to 2♠ and then overcalled opponents 3♥ with 3♠.
Partner did her best but 4 tricks was all she could muster - and a 'bottom'.
I have to admit I had 'words' with my partner afterwards, later I apologised and she apologised too. Clearly a misunderstanding and we agreed "not to let it happen again!"
Here is where I'd like suggestions...