Something yellow on my anus opening?

I noticed this yellow kinda thing on my anus opening. And it also seems wet kinda. I posted a pic (graphic). If anone could help me realize what this is? Should I be worried or not.

Sounds nasty. Thank God there's no picture

Saw someone on the embarrasing  bodies problems programme last year with this complaint, cant remember the outcome now, google it, and yes thank god there was no picture!