The following techs were found by speedrunners, and posted to the Chirpy Reverie Discord server. I later made a series of pinned posts in #cool-finds, with videos on how to do them (with the exception of the DDJ). The videos will probably need to be played in VLC Media Player on a PC.

DDJ (tap jump off):

• Hold up or up-forward while on the ground
• Do the same inputs as a dash jump
• Easier, more consistent, and faster than with "up is jump" turned on

Backdash:

• Touch the active side of a horizontal blue or red dash block
• Dash the opposite direction you usually would to hit the block
• You will hit the block, and travel in the same direction the block did

Nut Jump:

• Jump into specific walls in the game (see the attached video)
• At the point the screen starts scrolling, Chirpy will clip slightly into the wall
• You will regain your dash, and be able to jump off the wall for a frame
• Saves 2 X presses in the X Button Challenge (xbc) for Sunset Shore, as shown in this video

Ceiling Diagonal Dash Jump (CDDJ):

• Dash into a ceiling
• During the dash animation, if Chirpy is touching the ceiling, jump
• Chirpy will DDJ and gain his dash back
• Can be used to gain extra height on the corners of ceilings
• Timing is harder the further Chirpy is from the ceiling The first use for the CDDJ was found in SW by My_Life101. TASed by myself here:

Mosswall Dash Jump:

• Dash into a mosswall (the walls in UT and Grounds you can wall jump off)
• On the frame (before?) Chirpy touches the wall, jump
• Chirpy will dash jump and gain his dash back
• Sends Chirpy up the mosswall very fast :O

Mosswall Clip:

• Stand right next to a mosswall
• Dash down into the ground
• Super Spin Jump in the opposite direction of the mosswall
• Chirpy will clip into the wall, and start climbing up
• If there is a ceiling above the mosswall, Chirpy will come out on the other side of the wall as shown

FUNNY WALL:

• Touch a mosswall in the spin state (slidehop, backflip, ssj)
• If there is enough room behind a mosswall's wall-run hitbox for a Chirpy, he will clip straight through
• Chirpy will start a wall-run on the other side of the mosswall
• In the case of the original FUNNY WALL in Grounds, he will go onto the separate mosswall on the other side of the room

Under-Level Skip (ULS):

• Level collision doesn't go below the bottom of the screen
• In some rooms, Chirpy can dash under the level, on the edge of the screen, and complete it
• The first one found was in SW (see the video) using the water, but ULS's exist in UT, 1EX, and PPath as well

Wall Bounce (Uppies!):

• Dash up while under a mosswall
• Chirpy will bounce up; will not gain his dash back
• If the mosswall starts right above a ceiling, Chirpy can clip into it by dashing up

Dead Orb:

• Hit an orb
• Dash into it as it respawns, or hold X in the place where it will respawn
• The frame before the orb respawns, Chirpy will be sent in the direction as if he had hit a blue orb, but the orb will still be there. Into a blue orb (TASed by igorex95):
  Into a red orb: