A「grid raised off the floor or ground where birds roost」such as in a chicken coop, with「to let fly and let it fly again」meaning TO SCATTER, be careful NOT TO STEP upon by JUMPING OVER, HOPPING or SKIPPING over, to LAUNCH as with a blasting flow and discharge of material. Birds such as chickens sleep with open mouths while roosting, and during sleep the animals spontaneously defecate large amounts of fecal matter. Shit normally trickles down to all lower levels but sticks to everyone along its path. Wooden branches used as rails elevated off the ground for hens to roost upon when sleeping:
　「By instinct, chickens want to roost ('go to bed') in the highest point available, and be gathered together in a group for protection and warmth while they sleep. Your chickens will be happier animals if you play to their instincts when you are designing their living space. If you were to place multiple roosts inside your coop with some higher than others, they may fight to get the highest ('best') spots: to avoid this, you keep the roost at all the same level. …A chicken roost is a very simple board…or a wooden clothes rod like you would put in a closet, or even a thick tree branch that is about [2-3 inches in diameter].」
　　[　https://www.pet-chicken.com/why-chickens-need-a-roost/ 2014-09-29　]　
　Regardless of that previous explanation,「flying with repeated erection screwing and thrusting forward with small sitting person」also would eventually result in SCATTERING droplets, LAUNCHING a barrage, and in dynastic China would describe the foot or feet of a service provider that appear to HOP, SKIP, JUMP, LEAP, WAVE IN THE AIR, or be SENT FLYING by clients. It is perhaps no coincidence this glyph uses elements that appear to be「two no-longer-integrated feet」(羽) that have been turned inside out ('everted') after use by「repeated bobbing head of erection screwing, array of erect rods bobbing」(升). Significantly, literal bird wings do not function as flight instruments when everted, so the glyph seems to indicate no-longer-integrated feet after the flight of a client, or two. In fact, everting a bird's wings has the tendency to break the bones…

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: to fly
Japanese: rook, flying, leaping, flight, naught, zero, oh, flying fish, running out of points ), game ending due to a player running out of points, to jump, to leap, to spring, to bound, to hop, to fly, to soar, selling or divesting in unwanted stocks, hiding bad loans, to fire, to hurl, to launch, to make fly, to skip over, to omit, to drop, to run or drive fast, to gallop, to spread a rumour, to tell a story, to tell a joke, to remove, to get rid of, to transfer, to attack, to jeer at, splash, spray, soaring, to fly about, to flutter about, to flit about, to fly past each other, jumping match, running match, to jump at, to be attracted by
Unihan extended: fly; go quickly; dart; high
EDRDG: fly; skip (pages); scatter

Used within names (nanori)
あす　･　とび