puzzle

 ACROSS

  1 Resuscitation expert, briefly

  4 You might snap one with your BFF

  7 Parody

  9 One may pwn a noob

 11 What a mask blocks

 13 Treats like a baby

 15 *Certain geocentric paths

 17 Unit of land

 18 "Harold and ___" (1971 cult classic)

 19 ___ mot (witticism)

 20 *Experience auditory hallucinations

 23 Signal signals?

 24 Blood-filtering organs

 25 Religious subgroup

 26 Monkey (around)

 27 Lead-in to "gritty"

 29 Cardiologists, e.g.: Abbr.

 30 Nostalgic photo tone

 31 "Boo 2! A ___ Halloween" (Tyler Perry film)

 34 *2011 movie in which Jean Dujardin played a silent film star

 38 Academic URL ending

 39 Paul of "Knocked Up"

 40 Watson or Stone of film

 41 Couch potato's device

 44 Business name abbr.

 45 Colorado skiing destination

 46 Withdraw from the front lines

 48 Full of hot air

 50 Pizza seasoning

 51 Picks out

 52 With 53-Across, what lovers often have after ending their relationships ... or a hint to both this grid's shape and the word hidden in each starred answer

 53 See 52-Across

DOWN

  1 Quotation at the start of a chapter

  2 Jackpot

  3 Schlep

  4 Spanish for "father"

  5 Movie lover's website

  6 What a nun practices

  7 Jazzes (up)

  8 Ga. neighbor

  9 Get the ___ on (obtain evidence against)

 10 Snappy comeback

 11 Persian monarch

 12 Weasel with white fur

 13 Word you may chant at Oktoberfest

 14 IDs targeted by phishers

 16 Basks in the sun

 21 Ancient Romans' world

 22 Gas brand with collectible toy trucks

 23 Bug catcher?

 25 Kerfuffle

 27 Money-related question in an ad

 28 Apple tablet

 30 Repeatedly avoid

 31 Paris subway

 32 Figuratively, literally?

 33 Tool for cleaning a bookcase

 34 Moon of Neptune

 35 Typeface commonly used for memes

 36 Refines, as metal

 37 Gets awful reviews

 42 Thus

 43 Tropical hardwood

 45 Penne ___ vodka

 47 Ending for oct-

 49 "Life of Pi" director Ang

solution