das Gedöns
fuss
Colloquial and often derogatory for unnecessary effort, bother, or exaggerated fuss about something.
Mach doch nicht so ein Gedöns, es ist doch nur ein kleines Fest!
Don't make such a fuss; it's only a small party!

fuss / stuff
Loading your saved state.
fuss
Colloquial and often derogatory for unnecessary effort, bother, or exaggerated fuss about something.
Mach doch nicht so ein Gedöns, es ist doch nur ein kleines Fest!
Don't make such a fuss; it's only a small party!

The prefix 'Ge-' is often used to form collective nouns that frequently have a negative or derogatory meaning (e.g. 'Gerede' (talk/gossip), 'Geschrei' (shouting)). This explains the negative connotation of 'Gedöns' (fuss/stuff).
Was ist das für ein seltsames Gedöns auf dem Tisch?
What is that strange stuff on the table?
'Gedöns' (fuss/stuff) is a strongly colloquial and derogatory word. You should definitely avoid it in formal or polite conversations.
Er nannte meine Dekoration abfällig „Gedöns“.
He dismissively called my decoration 'Gedöns' (junk).
As a collective noun for 'Aufwand' (effort/fuss) or 'Kram' (stuff/junk), 'Gedöns' is always used in the singular, even when you are talking about many things. A plural form does not exist.
Bitte räum dein ganzes Spielzeug-Gedöns auf, bevor die Gäste kommen.
Please tidy up all your toy stuff before the guests come.
In the meaning of 'unnötiger Aufwand' (unnecessary effort/fuss), the fixed expression 'ein Gedöns um etwas machen' (to make a fuss about something) is often used.
Warum machst du so ein Gedöns wegen der kleinen Planänderung?
Why are you making such a fuss about the small change of plan?
theater
'das Theater' and 'das Gedöns' can both mean colloquially that someone is making too much drama or unnecessary effort. With 'Theater', there is often a sense that someone is reacting very dramatically or emotionally. 'Gedöns' is more about unnecessary bother, complicated preparation, or exaggerated fuss. Both words can sound negative. Learners may confuse them because in similar situations you can say: 'Mach nicht so ein Theater' (don't make such a fuss) or 'Mach nicht so viel Gedöns' (don't make such a fuss). 'Theater' fits better for excitement and drama, while 'Gedöns' fits better for unnecessary effort.

Am Abend vor der Reise nervt mich das ganze Gedöns mit Formularen und Listen.
The evening before the trip, all the fuss with forms and lists gets on my nerves.
Bei der Arbeit macht er jedes Mal ein großes Theater, wenn sich ein Plan ändert.
At work, he makes a big fuss every time a plan changes.