Here are the why&#x2F;hows as I understand them:<p>1) This is an informal shorthand agreed between people who already know each other in the particular context of work, so there is no surprise or ambiguity. Outside this context, I would use, and expect to see the dictionary sign.<p>2) It functions as an &#x27;in-group&#x27; slang, boosting cohesion and good will.<p>3) There is a certain humorousness in bending a symbol into an informal use. This is more pronounced in cases where the alternate meaning is irreverent or vulgar. I have no intention of expanding on the second point.<p>4) One does not have to be facing the SL speaker. The &#x27;t&#x27; symbol can be recognized from beside the person or even behind. Point 5 gives the rationale for this.<p>5) It can be communicated without changing focus or posture, allowing concentration on the task at hand without breaking the workflow.<p>6) Though &#x27;thanks&#x27; is a brief gesture, &#x27;t&#x27; can be signed and understood even more quickly. Just a flash of meaning.<p>7) The sign for &#x27;good&#x27;, while it is also used to communicate thanks and has advantages 4,5,6 listed above, can be ambiguous, violating the principle of least surprise (see point 1 above). It is more generic, while &#x27;t&#x27; is specific.