How to get plunger?

You get the plunger via the cleaning tools merge line which come from the broom cabinet.

Cleaning Tools

To begin with the cloth, which you merge to then bucket, then the sponge, then after that you'll get a plunger.

Broom Cabinet

To get the broom cabinet you'll need first the nuts and bolts, which merge to a handle then eventually a cupboard door then a broom cabinet, from that level you can start to get the items needed to get a plunger.