Word or phrase for becoming clumsy due to being overjoyed/happy

Solution 1:

They are deliriously happy (usually used as hyperbole):

deliriously happy

• It's because she's so madly, deliriously happy that she wants everyone else to be happy too.

[Collins] ...

delirious [adjective]

Someone who is delirious is unable to think or speak in a sensible and reasonable way ...

.............

delirious: [(2)a] marked by uncontrolled excitement ...

[AHD]

..............................................

Another possibility is to use ecstatic (again, usually used hyperbolically):

ecstasy

1a: a state of being beyond reason and self-control

2: a state of overwhelming emotion, especially rapturous delight ...

[Merriam-Webster]

Solution 2:

Giddy should do. Often in phrases such as giddy with delight or giddy with happiness.

Merriam Webster online: Giddy

1
a: DIZZY - giddy from the unaccustomed exercise
b: causing dizziness - a giddy height
c: whirling rapidly
2
a: lightheartedly silly : FRIVOLOUS
b: joyfully elated : EUPHORIC - was giddy with delight

The noun giglet does exist, meaning a giddy girl among other things, but I think I'd steer clear of it.