From the rctq FAQ, published reasonably frequently by whoever holds the "most conscientious person" crown -- its been frood (Wendy) lately. You can google in groups for FAQ + squish to get the complete posting. Here is the first bit:
========== What is a Squishie? "Rules of the Game"
Squishie protocol differs. "Squishie" is generic, of course. Anything that squishes in your mailbox (fabric-wise--we won't discuss vandals or kids with too much time on their hands) is a squishie. If you're involved in a swap ('you send me... and I'll send you...'), or you lose a bet, then of course the timeline on returns is worked out from the git-go. If, however, you're being squished as a 'welcome friend!/no reason at all' gesture, the "rules" are a bit grayer. I'd be willing to bet that the sender isn't really expecting a return squish.
*However*, the general mood of these squishies is "pass it on". When you get a chance to welcome someone else, or you see a piece that reminds you of someone on RCTQ, send your own 'no reason' squishie. It all manages to come back to you, in one form or another. One thing seems to be agreed-upon, however: PLEASE acknowledge the receipt of your squishie, and do so privately (through e-mail, not through this newsgroup). Whether you've received the fabric as a result of a swap, or as a surprise gift, the sender needs to know you've received it (but *only* the sender--no one else is interested). These same guidelines apply to sending squishies: if you wish to alert people to be on a lookout for some fabric, do so privately through e-mail. Sometimes it happens that the only way you can contact someone is through RCTQ. In that case, please refer to first names or e-mail addresses only. Many people have no wish to have their last names known or made public on/through the newsgroup... ===========)O( Anne > Er...help the terminologically challenged here. What's squishing (or should > I ask?).