To faegull is to evacuate your bowels into your own underwear and then use the faecal matter to express your distaste for someone or something by flinging aforementioned faeces at said individual or item at the same time as making a noise not dissimilar to that of an angry seagull.
This is an evolution of being seagulled. (see definition)
The poor stranger wondered what on earth had happened when the odd man on the train faegulled him. It was because he was talking too loudly on his mobile.