what instrument is HUGE?

uhm... Big and Weird-shaped aren't very helpful.

Does it have strings? The string Bass is the biggest of the stringed instruments. However: If it has 4 strings, it is a String Bass. If it has 6 strings, it is a Violone.

Does it have pipes? Many orchestras have pipe organs built into their Halls, which play as soloists or part of the orchestra for certain pieces. On the other hand, if may appear to have pipes, but also have a hammer-like beater: this is the Orchestra Bells.

Does it just have metal tubing, and get really big at one end? It's probably a tuba, if the tubing bent into an oblong shape, but if the tubing is bent in an "o" shape, it is properly called a Sousaphone (or Helikon.)

Is it partially wood? (Usually, the wooden parts are a deep red, and the metal parts and keys are silver.) It might be a Contrabassoon.

Is its weird shape because it is round like a drum, but pictured at an angle, and it has a large metal structure holding it up? It's a Bass Drum. (The largest bass drum used by a marching band is owned by the Purdue "All Americans" and is about 8' diameter and about 4" wide: it rides on a carriage made from a Ford Model "T" back axel and wheelbase: there's an article on it "Purdue Big Bass Drum" on Wikipedia.)

In order biggest to smallest for the large instruments

Grand Piano

Harp

Double Bass

Timpani

Tuba

Contra-bass clarinet

Contra-bassoon

Tuba(band)

Bass(orchestra)

those are the biggest instruments

Huge-double bass, tuba, contrabassoon. Huger- tympano (the singular if tympani), bass drum, harp. Hugest - piano, organ

The sousaphone is massive- it is almost worn rather than held, as it fits around the player. It is in the brass family.

http//en.wikipedia.org/wiki/Sousaphone

Contrabassoons also have a weird shape, and they are quite big. http://en.wikipedia.org/wiki/Contrabassoon

If it's weird shaped, it might be something like the contrabassoon.

Full size double bass, tuba and timpani.

A concert grand piano!

a grand piano

a double bass

a contra bass

A harp is quite large!