Saw this far too real post on McSweeney’s called ‘Let me translate my emails for you’. Highlights:
“I’m just checking in.” = Where is that thing you promised I’d have by now?
“Sorry to bother you again.” = Why can’t you do your fucking job?
“Sorry if I somehow missed your email.” = We both know you never emailed me.
There is probably no really polite way to harass HR departments to give/confirm an internship for you. But these are a couple of handy euphemisms that will at least let your passive aggressive side out.