CTFD: An intialism for "Calm The Fuck Down" mosty used in chat forums and email, but having some leakage to vernacular usage. (see-tee-eff-dee)(emphatic)
"During the CoVid-19 lockdown panic with all of those empty shelves in the supermarkets, I wanted managers to put up signs link, 'Attention customers: please CTFD, you don't need to buy 25 rolls of toilet paper'."