You may be suffering from transient global amnesia, which means it's not your fault!
So, you met a cute guy or girl at a bar and things went well enough that you woke up next to this stranger the following morning, only to realize you forgot their name. Besides drinking, is there a scientific explanation on why you don't remember a hookup's name? Are you just really insensitive and shallow because you were more focused on bringing this person back to your place instead getting to know them? Or, is your brain tricking you? The answer could be the latter.
University of Sussex neuroscientists found that we tend to forget names of new people due to memory lapses. During these memory lapses, our brain stops memories from being formed possibly to prevent the brain from being overloaded with information. This information, however, could be recalled after several hours of learning it, so it's not completely gone — just inaccessible for a period of time.
That does seem to make sense since your brain is probably remembering more things about the person — like the fact they like your favorite band, or what they do for a living, and decides that remembering a name could take the back seat to this information.
But does sex also have an effect on our memory? Turns out it does and the name for it is "transient global amnesia". This rare condition is triggered by the excitement and change in blood flow from sex and other strenuous activities and tends to make you forget recent memories. This is possibly a reason why make up sex is a thing. It makes some people forget what they were even fighting about! Another strange thing about this condition is that it tends to occur in people in their 50s and 60s and it tends to happen only once.
So next time you forget your hook up's name, just remember it could possibility be the cause of a memory lapse or you are suffering from transient global amnesia. If it's the second you should probably go see a doctor.