The Spanish culture in general, and that of tapas in particular, is about sharing: spaces, food, wine... Porrones are made for the latter. Here are Omar's tips on using a porrón without spilling wine all over oneself. Come give it a go?
When I was a kid in every familiar meetings (matanza, Christmas, birthdays...) we were allowed to have a swallow as long as we could without stain ourselves so that we could learn how men -and women- should drink.