Here is an idea.

You brought a condiment to work.
Put it on the fucking condiment shelf where it belongs.
Understand that condiments are universally accepted to be group consumption.

I’ve worked & lived in communal living arrangements for more than a decade (Paramedic). You are the problem.

As a side note: If I saw that & I actually believed it was breast milk, I would immediately throw it out. Reposing unsealed containers like that is unsafe for baby. That is why breast pumps are closed systems, and use screw lids with gaskets.