My girlfriend a good many years back would help me. If I had a big poop that wouldn't come out or got stuck part way out. She would lean over me while I leaned forward on the toilet and with a hand on each of my butt cheeks and her fingers surrounding my anus she would help stretch it open as wide as possible. She would massage it and stretch it wide, and when she could see if it started to move out, she would tell me and I would push harder. It really helped me poop many times. I would love to have another helper like her now.
As someone who has a lifetime of chronic constipation I rely on daily irrigation at home and Microlax mini enemas when we travel. Occasionally, and not nearly enough, I go for a colonic.