It's from where?

Denim cloth takes its name from the French phrase serge de Nîmes (‘serge from Nîmes’). Denim as we know it today was first produced in Nîmes, France.

Chihuahua

A breed of dog, native to Mexico and named for Chihuahua, a state in the northern part of that country.

Jeans.

From Gênes, the French name for Genoa, one of the early centers of producing a cloth which originally was actually distinct from denim.

Champagne (hint: by law if it isn’t actually from this place it’s not “real” champagne).

Champagne, originally vin de Champagne, is a type of sparkling wine named for, and first made in, the former French province or county of Champagne.

dungarees.

Dongri, a village near Mumbai.

cheddar

A village in southwestern England, which first produced the eponymous cheese. Sadly, it’s in Somerset, not Cheshire (Cheese-shire).

astrakhan

The fur was introduced to Western Russia by Tatar traders from Astrakhan.

Strontium

From the village of Strontian, in Argyllshire. The English name of the village is in turn an anglicisation of Sròn an tSìthein, the nose (or point) of the hill of fairies.

If we’re doing the elements, copper.

Ooh, good one. I’m a little hazy on the direct derivation, but I’m pretty sure it comes from the Latin name for the island of Cyprus, known since antiquity for its copper mines.

baloney

That could mean the name of a type of sausage from Bologna, a city in Italy (also called “bologna”).
Or it means utter nonsense, from 1920s-era vernacular still in use.

mustang (horse)

I’m not aware of any toponymic origin for mustang, and Merriam-Webster agrees with me.

I’ll offer one, hoping that it’s not too obscure:

coach

From a medieval Detroit outside of Budapest called Kocs.
Bedlam

From St. Mary Bethlehem Hospital, a medieval priory-turned-asylum notorious for its poor care of patients.

Ulster

Victorian era overcoat named for an Irish region, made by a manufacturer from there

Balaclava

Another piece of clothing whose name derives from the Crimean war; a balaclava is a knitted winter hat that covers part of the face, named after a town near Sevastopol and the British troops who fought there, wearing the headgear.

Norfolk.

The jacket or the briefcase?
I believe both get their names from the county in East England or the Duke thereof.

ETA: Appears the briefcase was made by a firm on Norfolk Road in Sheffield.
Mayonnaise

A sauce of eggs and oil, according to legend created by a French admiral’s cook, while besieging the Spanish port of Mahón, on the island of Menorica. Although I recently had a dispute over this with a Spanish cow-orker, who insisted it was a native Spanish sauce. In any case, it’s named after Mahón.

Gin.

Hm. According to Wikipedia:

The name gin is a shortened form of the older English word genever (related to the French word genièvre and the Dutch word jenever. All ultimately derive from juniperus, the Latin for juniper

Are you thinking that it comes from Geneva? Or that “juniperus” is a toponym?

I don’t have an interesting one on offer, but to keep the game going:

Cognac

Like the earlier champagne question, it refers to a brandy, the source of which is wine made from grapes grown in the Cognac region of southwestern France. This is the reason “all cognac is brandy, but not all brandy is Cognac.”

jodhpurs

-“BB”-

Yes, you’re correct; I mistakenly thought gin came from Geneva.