I’m not sure if it is as bad as burning pee but seeing some dreaded unwanted pest in your tank has to be like getting a call from a one-night stand informing you of his or her not-so squeaky-clean status.  For me that scourge is red planaria.  Yeah, yeah “I swear I used protection! I dipped all my frags,” yet the little bastards still got in and are now having wild, unprotected (and sometimes asexual) orgies in my reeftank.  What started out as a few is now into the hundreds if not thousands and I am embarrassed to tell my reefing friends.  When people come over to see the tank and then accept my offer to take some frags home I need to give them a caveat before I let them leave.  The conversation usually goes something like this:

me: (as ufct is walking toward the door) Ummmm, do you have Coral Rx or flatworm exit?

unsuspecting free coral taker: No, why?

me:  There is something I have to tell you, you might want to take a seat.

ufct: … (looks at me strangely because they know what’s coming) uhh, O.K.  (they sit)

me: I haven’t been completely forthright with you.   They are completely harmless, they don’t eat acros.

ufct:(interrupting me) WTF ?@!

me: I have (pause for dramatic effect)… bugs, worms to be precise.

At this point, their response depends on a couple of things.  Is the ufct a  noob or a vet? Have they had flatworms before?