which day of the week

to meet with, see, meet again or for the first time / to come across, meet by accident, bump into / to gather, to come together / to receive guests etc.

day of the week

(adverbial particle, dismissive, derogatory) emphasizes disgust, contempt, or otherwise negative feelings of the speaker: whatever

whatchamacallit, X

What? What did you say?

what number, how many (used with a counter) / (used with も) many (used with a counter)

nothing

what is this?

if you don't mind, if you like, if you're so inclined