bubble, bauble, bobble

Bubble or bubble means a sphere or globe of gas or air, contained in a shell or envelope of liquid--
He got a good picture of the dog chasing a bubble.
Tell the children to put their bubble gum in the trash when they are done with it.

Bubble may also mean to boil or effervesce, so as to make bubbles--
When it begins to bubble, turn down the heat.
When you drop in the tablet, the mixture will bubble, so use a large glass.

Bubble may also mean a delusion, or a form of wild speculation in stocks or securities--
I hate to burst your bubble, but you're not likely to win the lottery.
He lost most of his savings in the dotcom bubble.

Bauble or bauble means a trinket or ornament, particularly a cheap one--
He buys one cheap bauble after another; he has them all on a shelf.
Just get her a little bauble for her birthday, something she can wear.

Bobble or bobble means a repeated jerking movement, or to make such a movement--
I can see his bobble from here; he must have headphones on.
The dog figurine will bobble its head if you move it.

Now that you know that, you can say--
"We bought her a little bauble, a duck that will bobble its head and blow a bubble when you press the switch."

Note--"Bob'll" ( rhymes with bobble ) is a contraction ( short, informal form ) of "Bob will", meaning a person named Bob ( always capitalized ), at sometime in the future ( will )--
Wait a few more minutes; Bob'll be here soon.
"Bob'll or bob'll may also be a contraction of "bob will", meaning a small, dangling object ( bob ) at some time in the future ( will )--
This bob'll keep the line where I can see it.