Idiom: “An expression unique to a language, especially one whose sense is not predictable from the meanings and arrangement of its elements, such as kick the bucket a slang term meaning ‘to die’, which has nothing obviously to do with kicking or buckets.” 
As noted in part 1 and part 2, idioms can bring a language to life. They can help explain complex concepts in easily understandable images. They are, however, potentially problematic for non-native speakers of a language as they may rely on unfamiliar cultural references. Beyond that, many commonly used idioms have been based on outdated and incorrect views and dubious racial and sexual stereotypes. Here are seven more for your consideration:
“Cotton-Pickin’” as in “Are you out of your cotton-pickin’ mind?” or "Keep Your Cotton-pickin' Fingers off"
A phrase from the US South. The exact origins of the phrase are somewhat murky, but its use predates the American Revolution. On pre-civil war Southern plantations, the phrase was associated with the slaves who toiled in the cotton fields, and use was a reminder of their status. It was also used with others as an insult, suggesting the recipient was of low status.
In the mid-twentieth century “cotton-pickin’” was revived by movie writers and became part of the vernacular. Slavery is now considered a Crime Against Humanity and “cotton-pickin’” should be retired.
“Long time no see” and “no can do”
Both these phrases originate in pidgin English, a variant of English with reduced grammatical complexity and a smaller vocabulary. Originally pidgin developed to allow communication for business (“pidgin” meant “business”) between British traders and Chinese merchants. The term “pidgin” has since been applied to variants of English with many other languages. There are some commentators who argue that “long time no see” possibly originated with European settlers mocking First Nations’ linguistic patterns but in either case these phrases have been used to mock non-native speakers of English and should be dropped from current discourse.
“On the warpath”
One of many descriptive phrases created by European settlers. This, and others, reinforced the idea that the Indigenous peoples of North America were violent “savages” and “heathens”, rather than peoples defending themselves from genocidal invasion. Hollywood Westerns perpetuated such language; it’s time to leave it behind.
“Low man on the totem pole”
Commonly used to describe the least valued person in a group, the phrase is based on a misconception by European settlers.
Totem poles are carved from tree trunks and depict symbolic forms of people, animals, and supernatural beings that are meaningful to the family or clan. In the culture of Indigenous peoples of the Northwest, totem poles have sacred value. As pieces of art they are respected worldwide.
What is the misconception? Ironically, the lowest part of a totem pole has representations of the highest status people in the community. The carvings closest to the ground are the most easily seen and the figures placed there support all that extends above. “Bottom of the food chain” and “low in the pecking order” are alternatives—if you need hierarchical idioms.
Commonly used to describe being a victim of sharp practice or being cheated, the word comes from Gypsy, a pejorative term for Romani people, also known as Roma. Romani are stereotyped as thieves, cheats and con artists, hence “gypped.”
“Cheated”, “ripped off” and “conned” are inoffensive replacements.
Mumbo-jumbo is used to describe (and often dismiss) language that is hard to understand, as in, “I don’t care about all that legal mumbo-jumbo.” It was also used to dismiss the spiritual beliefs and rituals of colonized peoples and has become a general pejorative term for ritual and superstition.
Mumbo-jumbo comes from the West African language Mandinka. The term is a British approximation of “maamajomboo”, a masked male figure who functioned as an arbiter of marital disputes in the polygamous society. The costumed man would dance and chant and shout outside the dwelling and then rule on the dispute.
“Gibberish” and “nonsense” are replacements free from racist and condescending connotations.
Current use is often casual and informal, referring to people considered useless and inept, or failing nations or enterprises that are beyond financial redemption.
The origin of “basket case” is tragic, however, since it refers to WW1 soldiers who had lost all four limbs and had to be carried in baskets as a result.
When used to describe people, it is often applied to those who are unable to function owing to anxiety or emotional stress, so there is more than one reason to avoid its use.
 Oxford Companion to the English Language (2nd Ed.)