muddle up

muddle up (third-person singular simple present muddles up, present participle muddling up, simple past and past participle muddled up)

1. (transitive) to confuse (one or more objects with another object or other objects)

   Whenever I meet the twins, I always muddle up their names. I call John Jim, and Jim John.

2. (transitive) To mix together

   muddle up the letters in the word, and try to make new ones.