I didnt used to get the 'your too serious' thing when I was younger, but I have had it a little bit as I got older. I dont like it when people say that though, coz I dont think of myself as a serious person, and I do mess around quite a lot

I think it probably ties in with the delta quadra being refered to as the most mature/grown up quadra. I reckon ESTj's must get it all the time.