Seriously, what's with the joint couple accounts? Even if you two are like, thisclose, you are still two separate people. Even if you share a computer, you can have two accounts. There is no logical explanation for sharing an account, aside from the fact that one or both of you are insecure, jealous, possessive or all of the above.
If you have friends, you can be assured that they're annoyed they have to communicate with whatever portmanteau you've created for yourselves instead of whichever one of you they actually want to speak to. Every couple should maintain personal space and respect one another's privacy, so if we're forced to message Bennifer or CindyAndPeter, we're definitely going to have some default judgements on the health and overall sanity of your relationship. Proceed at your own risk.