Are You Serious?

In the midnight game Friday night, we were playing against a pair of sober guys, but at least they were accepting of the laughing and some silliness that is natural at midnight games. We had just been laughing about something and on about the 4th board, I opened 1H, Sean bid 1S, alerted by me. After a couple of seconds, rho asks did you alert? yes. what does 1S mean? he promised only 3 spades. (slight hesitation, still a lot of giggling going around) are you serious? yeah. okay. A couple of hands later, I open 1D, partner responds 1S, alerted as promising only 3, and I rebid 1NT, alerted. the opponent asks again what it means? he has exactly 5 hearts and at least 2 spades. (another couple of seconds hesitation) are you serious? yeah. that's our system. that was amusing.