Apparently the expression was originally walking on eggs and later morphed to eggshells.

https://www.grammarphobia.com/blog/2010/05/walking-on-eggs-or-eggshells.html

Edit: Sometimes I think President Trump does this on purpose, but maybe he just grew up hearing the original version.

Apparently the expression was originally walking on eggs and later morphed to eggshells.

https://www.grammarphobia.com/blog/2010/05/walking-on-eggs-or-eggshells.html