you know you're an XXXX when grandma's skin looks like the skin you want to flay and wear around the house to tuck your weiner in (because it has extra compartments in the wrinkles and tanning it will take half the time)
1) you get really interested in something to the point you almost can't talk about anything else (eg. post 150 times on typologycentral in a few weeks just because MBTI is your shiny new interest)
2) you see 10 threads like "ENTJ non-villains", "INFP villains", "ESFP comic dumb characters" and you make a new thread called "villains and heroes of type XXXX" trying to find examples for each of them.
3) you get frustrated other people aren't posting in a general thread like "you know you're an XXXX when", preferring a particular thread called "you know you're an ESFP when" or something.
4) you post this thing into a thread called "you know when you're an XXXX" instead of making a new thread called "you know you're an ENTP"
5) you actually see no difference between points 2), 3) and 4) of this post and want to combine them into one point
Edit: 6) You check your general theory by looking at the profile of the original poster of this thread. Yes, an N, my understanding holds!
7) You edit your post a few minutes after posting to add 6) and 7) (instead of first looking and then posting like the judging types would do)