I've seen this referred to as a 'cock-thumb' proposal. As in, you ask for the greater sacrifice (cutting off the first) and hope they answer proposing the small

I've seen this referred to as a 'cock-thumb' proposal. As in, you ask for the greater sacrifice (cutting off the first) and hope they answer proposing the smaller sacrifice (to cut off the second) instead; which is what you wanted in the first place.