Developers make your own Tip jar, or make one for a friend or customer.

http://www.imvu.com/shop/product.php?products_id=11531067

This mesh is a jar that has an sign on it and above that are opacity enabled. Make a tip jar with any message you want on it.

To customise the link what you need to do is download the Link.xml file, and open it in a text editor, look at the end of the url and you can see where you change the message, enter the tip amount and the person who will receive the tip.  Save the Link.xml file and then move it into the product assets folder just drag and drop. You can test this if the client, if the right link does not show up try again.

Right click and save the Link.xml file, edit in a text editor, save and move to file assets folder, hit apply.

http://www.textures123.com/meshes/tipjar/Link.xml

Here's the parts of the xml you need to change, only edit the bit after the equals sign. Chnage the message, amount if you want and payee

&greeting=Here's a Tip 4u !

&payment_amount=500

&payee=4u