This sage piece of advice was given by the contributor’s ex. It is a nice mashup of “don’t count your chickens before they hatch” (don’t make plans based on future events that might not happen) and “don’t put all your eggs in one basket” (don’t focus all your attention one thing or area). Both phrases start with “don’t” and both involve hens (chickens and eggs) so there is bound to be confusion. Apparently after saying this he rationalized the phrase by noting some eggs may fall out or break as you’re putting the basket down. This is true. Thanks to Zozie for sharing this one!
This is another in the collection of what I call “Idiom Overloads”. It is a mashup of “not the brightest bulb in the pack (or chandelier)” (slow-witted or dull person) and I think “don’t put all your eggs in one basket” (don’t focus all your attention on one thing). The speaker was probably imagining a bulb in his mind but eggs also look a little like bulbs. Since many of the idioms describing dull or stupid people have an “in the (blank)” part of the phrase he then added “in the basket.” “Basket case” (emotionally unstable person) also may be in the mix.
The various sayings describing a dimwit are similar sounding and involve something in a unit or package that is unique, hence the confusion. I call this phenomenon “idiom overload”. I have posted other variations on this theme – see https://malaphors.com/2015/12/07/youre-not-the-brightest-toolbox-in-the-shed/ and https://malaphors.com/2013/06/24/not-the-brightest-tool-in-the-shed/.
Another example of idiom overload is describing the obvious: “is the Pope Catholic?”. “Does a bear shit in the woods?” etc. These get mixed up regularly. A tip of the hat to Josh Berry for hearing this one and sending it on!