Why would he joke about something having a kid what could it mean?

I’m sorta talking to this guy & he started lying and joking about how he had a baby & how he might have a daughter on the way too. he brought his imaginary kid into conversations the next day when he found out i used to talk to his friend a while back & i lied about it out of embarrassment & because the guy in the past isn’t important to me i should’ve been honest from the start i know. but like he kept on joking around knowing i knew the truth & would give me the silent treatment until i said goodbye & days later he reached out to me.
Why would he joke about something having a kid what could it mean?
Post Opinion