Was this at a restaurant? bar? neither
Were the drinks coffee? (you missed that up there.) So, I did. Mea culpa. All the stranger, as I find coffee hard to ignore in general. Yes, the drinks were coffee.
Was this interpreting 'this' in a broader contextual sense, as in 'why they were there in the first place'
being done for fun? no
business reasons? yes
was attendance mandatory? yes
Was the instructor the boss? no
Is the primary purpose of the pouring to leave a stain? no
Is the stain intended to be removed? yes
As a later distraction for a janitor? not relevantly
Were the drinks hot? yes
Cold? Relevant? somewhat
Were the drinks spiked, poisoned, or tainted in some way? no