Theme: Vowel Progression - Adding, in order, a vowel to B_LLY and finding an appropriate phrase to begin with it.
16A. Big stink : BALLYHOO
20A. Amateurish dive : BELLY FLOP
37A. Bearded fairy tale trio : BILLY GOATS GRUFF
50A. Mumbai-based film industry : BOLLYWOOD. India
58A. Hired hoodlum : BULLYBOY
(rabbit, rabbit) Argyle here. A grid spanning entry and some overlapping of the other entries, neat. Two ten-letter downs. Decent fill, although the nitwit anon will complain.
Across:
1. Scottish hat : TAM
4. Cries out loud : SOBS
8. Dull sound : THUMP
13. Wharton's "The __ of Innocence" : AGE. Edith Wharton (1862 – 1937).
14. Summer Olympics event venue : POOL
15. Covering for "piggies" : BOOTIE
18. Stored in a database, say : ON FILE
19. Rural storage structure : SILO. Most farms are replacing the iconic tall cylinders for trench silos these days.
22. Opposite of a big star : NOBODY
25. "__ a trap!" : IT'S
26. "The Ballad of John and __" : YOKO
27. Men : HEs
28. Bearded flower : IRIS. Anyone we know?
32. Barely get, with "out" : EKE
34. Added a chip to the pot : ANTED
36. Maine college town : ORONO
40. Cartographer's book : ATLAS
41. Oven setting : BROIL
42. Word in most Commandments : NOT
43. Finger-on-hot-stove reaction : [YEOW!]
44. Sinister : BAD
45. Neuter, as a horse : GELD
47. Seasonal potable : NOG. The season approacheth!
48. Stand the test of time : ENDURE
55. Protected inlet : COVE
57. Camden Yards ballplayer : ORIOLE, Will they make it to the World Series?
61. Long-lasting resentment : RANCOR. A word that sounds like what it is. Is there a term for that?
62. Frozen drink brand : ICEE
63. Outlaw Clanton : IKE. He didn't like the Earps.
64. Gather a bit at a time : GLEAN
65. Student's book : TEXT
66. Composer Rorem : NED. He made an opera out of "Our Town". Wiki.
Down:
1. Settings for columned documents : TABS
2. From the top : AGAIN
3. Mountain Dew competitor : MELLO YELLO. 52.5mg of caffeine per 12 ounce can; Mountain Dew, 54mg of caffeine per 12 ounce can. If you were wondering, Tab has 46.5mg of caffeine per 12 ounce can. Source.
4. Undercover agent : SPY
5. "__ la la!" : OOH
6. Word with hatch or prize : BOOBY. Yes, he said, "BOOBY", now settle down.
7. Gin fizz fruit : SLOE
8. Broadway awards : TONYS. If the theater is off of Broadway, then it's the Obies.
9. "The Tao of Pooh" author Benjamin : HOFF. The book.
10. Either of two Monopoly sqs. : UTIL. (utility, either water works or electric company)
11. Venus de __ : MILO
12. Little chirp : PEEP
15. Makes a mad dash : BOLTS
17. Western wolf : LOBO
21. Wasn't honest with : LIED TO
23. Gives a thumbs-up : OKAYS
24. Second of two bell sounds : DONG
27. Caught wind of : HEARD
28. Outlet store abbr. : IRR. (irregular)
29. Tournament in which you play everyone else at least once : ROUND ROBIN
30. Facts, briefly : INFO
31. Tender-hearted : SOFT
32. Site for cyberbidders : eBAY
33. Flier on a string : KITE
35. Trinidad's partner : TOBAGO. The Republic of Trinidad and Tobago lies just off the NE coast of Venezuela.
36. Made goo-goo eyes at : OGLED
38. Murphy's __ : LAW. "Anything that can go wrong will go wrong."
39. Communicate with hand gestures : SIGN
44. Leafy hideaway : BOWER
46. Charlie Brown's tormentor : LUCY
47. Hosiery material : NYLON
48. Draw forth : EDUCE. The Latin root, ducere, means to lead.
49. Bring to mind : EVOKE
50. Tennis great Bjorn : BORG
51. Like some doctorate seekers' exams : ORAL
52. Queue : LINE
53. "Livin' La Vida __": Ricky Martin hit : LOCA. If you don't remember it, far be it for me to remind you.
54. "In memoriam" write-up : OBIT
56. Viewed : EYED
59. Superman nemesis Luthor : LEX
60. Allow : LET
Argyle