An article from the New Statesman today included the passage:
I stopped reading after “she had another thing coming”. What was coming? A promotion? A cup of coffee? Surely what was meant was that her rumination would require further thought – she had another think coming. The Ngram view (for what that is worth) shows the ‘coming’ form taking off from around 2000 and becoming the more usual form today.
It is a curious phrasing. The folksy etymology often attributed to American usage but one suspects that anyone who thinks that has another think coming.