Collocations for pants - noun

pair

pull on, pull up
drop, pull down
wet
He was so frightened that he wet his pants. (BrE, AmE)

bra and pants

long, short
corduroy, cotton, denim, flannel, leather, linen, polyester, silk, wool, etc.
stretch
pinstriped, plaid (AmE), striped
jogging (esp. BrE), sweat (usually sweatpants)
riding
cargo (BrE, AmE), flared, flat-front, low-rise, pleated
cropped
ripped
tailored
casual, dressy
dress
camo (informal), camouflage
parachute (AmE)
baggy, loose, loose-fitting
skintight, tight
drawstring
pajama (AmE)
matching
a brown vest with matching pants

pair

unbutton, undo, unzip
drop, pull down
pull on, pull up

leg, pocket
suit

in pants