expression
if things go wrong; if one is careless; at worst
Fixed adverbial expression used to warn about a possible negative outcome. Often implies that a small mistake or bad luck could lead to a serious result. Similar in tone to 'if you're not careful' or 'in the worst case'.
下手をすると大けがをするかもしれない。
If you're not careful, you could get seriously injured.
この計画は、下手をする
If things go wrong, this plan could end in a huge failure.