Mixed metaphors can do a little more than sing: in Dutch they sometimes might be a compensation for a language limited in words. So, I do use mixed metaphors and moreover: lately I translate English expressions litteraly to express what I feel or think. Very much against the rules, but I like it.
“Erg veel tegen de regels, maar ik vind het leuk”
“dat maakt u denken” (It makes you think).
Since I’m not in school anymore, there’s no punishment to that;-). However, I haven’t tried it in professional writing and I wouldn’t advice it.