I shit my pants at an after-school daycare I attended during 1st grade.
I really had to shit and got up from the snack table to ask permission to go to the bathroom. They daycare ladies were talking to each other and refused to acknowledge me, and I was the kind of kid who was too shy to speak up first.
So I just sat there holding it, breaking out into a sweat, shifting from one foot to the other, until finally one of them looked down at me annoyed and sarcastically listed "yeeeeessss??"
I asked if I could go to the bathroom and then ran off in that direction without waiting for a reply. I remember making it all the way to the stall, dropping my underwear and hanging my ass over the seat, except I didn't get far enough and it all came out in my underwear.
This had never happened and I had no idea what to do. I scooped the main mass of it out with toilet paper, but there was still large streaks of it embedded in the fibers of my underwear. For some reason I didn't think that would be noticeable.
I put my underwear back on and walked back to the snack table. Shit was smeared all over my ass from walking in it. As soon as I sat down a wave of disturbance made its way through the other kids and they almost immediately discerned that I had shit myself.
I still vividly remember the child next to me, turning his looming, stupid face right towards my own, eyes closed and nostrils flaring, mouth wide open in a half grimace half laugher, and screaming "HE POOPED IN HIS PANTS!!!!"
The daycare workers were never kind, but when they found out what happened they instantly hated me and didn't even try to hide it. They cleaned me up the best they could and called my parents to see if they could leave work a bit early to come and get me. By the time my parents got me home I had dried shit all over myself and developed a rash.
I felt humiliated and cornered during the entire event, and it was a trauma that I didn't get over for a very long time, as far as my early 20s, I was afraid of being in a situation where I could not escape (like a test at school or a band concert), and having to suddenly shit and being able to do nothing about it. This nervousness would, ironically, disturb my stomach until I actually had to shit. In middle school I used to throw up my breakfast every morning because I was afraid that if I didn't I would have to shit on the bus. I was probably malnourished and used to get horrendous stomach cramps. I used to spend a lot of time romanticizing the ancient past were primitive humans could shit wherever they wanted without having to look for toilets or follow social etiquette. By the time I was 17 I was almost entirely agoraphobic. I almost failed my senior year of high school because I refused to go to school or leave the house. I missed out on scholarships because of this, I missed out on friends, I missed out on nutrition and health.
When your coworker returns you should offer him solace and compassion.