which one doesn’t belong and why

Milkshakes don't come in bottles.

And a milkshake is made from a combination of ingredients while the others are full beverages on their own.

"juice" because it is completely non-specific?

"A milkshake" is partly specific: we know that a milkshake is made of milk and something else.

we know exactly what gin, whisky ("whiskey" to North Americans and Irish people) and milk are.

"juice" could be anything - carrot, tomato, orange, cranberry, we just don't know.

IMO, A milkshake is a drink with milk, and gin is a kind of whiskey, so these two pairs go together. The odd one out is juice.

Gin is most definitely NOT a "kind of whiskey"! They are both distilled spirits however. Guess you must be an abstainer, Roberta.

You're right, contrex, I don't drink. Had my spirits mixed up. Sorry.

Cancel my suggested answer.

Here's another: A milkshake is a drink with milk. Whiskey and gin are drinks with alcohol (hope I got that right). These pairs have something in common. Juice is still the odd one out.

Milk is the only thing that has not undergone mixing, preparation or processing unless you count pasteurisation.

Milk doesn't have an e in it?

Neither does gin.

Milkshake is a compound word, whereas the others are not. In British English, they tend to be called "milk shakes" rather than "milkshakes".

Again, a milk shake is a mixture, the others are not.

According to Google, the question features in a number of online "IQ" tests. It is a good idea to treat these tests with a great deal of caution. Many such tests are junk: very badly designed and using badly written questions. They often contain bias due to cultural presumptions by the test creators or just plain ignorance. Whole books (and doctoral theses) have been written about this.

Results can be skewed essentially meaningless and many critics find them to be of very limited usefulness indeed, especially outside controlled conditions, (e.g. on websites!)

For example an IQ test which was set for schoolkids in Mexico asked "What do you find fish and salt?" The "answer" was supposed to be "The sea", but a higher proportion of inland dwelling kids answered "The table".

How culturally presumptuous of the milkshake to be in a bar with the others.

It would have its close relative, the "milkshake" for company.

thank you all for your input. I'll be posting more!

Of course I meant to type that it would have its close relative, the milk for company.