Some 20 years ago, the Rickeybird hurt his left (and preferred) foot after a particularly apocalyptic battle with an evil hanging toy that was about twice his size; I banished it thereafter.
So the vet (also a bird lover/owner and a dear friend) looked at him and said he was fine, probably a bit sore, but didn't need anything more than a week's healing or so. He was hesitant to step on it, didn't want to return to the cage perch after I would have him out... I indulged him... went through all kinds of hassle and care and extra love and solicitations and treats to get him to go back on the perch. A few days went by... I was unaware that he was developing a new 'behavior'.
After a week, everything looked fine, but he still seemed "unable" to make that first step with his poor injured left foot. My friend came over and I demonstrated... poor bird just couldn't do it! His foot was paralyzed!!! She took him from me and placed him on the perch with ease. Repeated it. Then I tried... again, his poor 'disabled' foot just couldn't function!
Yep, he was playing me! My friend and I laughed and laughed! He was smart enough to trick ME, but not smart enough to avoid giving himself away with somebody else! Now that I knew what was going on, I pretty quickly got firm with him and the issue was resolved.
But, mannnnnnnn...
He played me!