Depending on what type of magic you're into...
Trouble is, if it's anything 'mental' then she'd be an instant candidate for suspicion of being a stooge (Mrs Seige is always accused of being 'in on it').
However, ILLUSIONS are a different matter.
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FIRST SUGGESTION
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A GREAT effect to perform that is inexpensive and rather exciting is the old 'twisting head' illusion, which can be done with a box, bucket, or anything that will cover her head.
The premise could be: "Don't you ever wish that sometimes your woman would turn a blind eye? They seem to have eyes in the back of their head, and always seem to be watching you. Almost like an owl!"
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SECOND SUGGESTION
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Women are very delicate beings (well, most of them...!)
Why not do a candle thru arm, or other such illusion? Sure, it's fun to do these things to yourself, but if your other half does them, you can concentrate on being the magician.
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THIRD SUGGESTION
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On the 'delicate' women theme, why not put her at danger?
http://www.magicshop.co.uk/STAGE_ILLUSI ... .1151.html
Something like this.
There's also a book available by Andrew Mayne (who is the RazorWire author) which explains how to build stage type illusions...
http://www.magicshop.co.uk/STAGE_ILLUSI ... .1410.html