Some companies purposely have a laid-back culture. Not a 'bro' culture, but a friendly, social one - that includes jabbing and jiving.

I love those beanbag-chair, not corp environments. Not everything that isn't corporate is 'unprofessional'. Wearing trainers to work was unprofessional, until it became established; now tech CEOs compete on who has the most expensive sneakers.

> If HR was involved, it's because someone was out of line or just doesn't understand how adults manage boundaries, in which case he should be warned and, if the case merits, punished.

I assume you mean the person who said it? It's also possible the person who reported it doesn't know how to manage relationships, or had some other motive in reporting this to HR - you can speculate either way.