Standing up while bent nearly in half, with the torso nearly horizontal and the legs (or at least thighs) vertical, possibly with the ass sticking out.
If they are only angled slightly forward, closer to 45 degrees than 90 degrees, they are leaning forward instead. If the hands and knees are on the ground, it's all fours instead. If the hands and feet are on the ground, it's bear position instead.
Pixiv
Twitter
Bluesky
Weibo
Lofter
Tumblr
