Under the iTunes in the Cloud section, click Manage Devices. (If you haven't associated any devices with your Apple ID, you won't see the Manage Devices section.) Information about each associated device appears. Next to each device, you can see when it associated with your Apple ID.
The real reason why the burp smells so badly is hydrogen sulfide (H2S). If you eat foods that have sulfur proteins in them then you may find yourself burping the H2S, which will smell like rotten eggs. The sulfur reducing microbes in the intestine digest the proteins and release the gas.
When you have excess air in your stomach, it usually comes out as a burp. Usually the burp will have a smell of the food that you ate, but sometimes it will come out smelling like rotten eggs. This is a condition that is known as sulfur burp, and they can be very embarrassing and unpleasant, especially if they happen in the presence of others.