General petty and wholly unnecessary one-upmanship.

The term is derived from the fact that partakers in such tomfoolery are usually trying to compensate for the fact that they have very small peni.
Situations where people could be accused of indulging in smallpenisary:

Louis: Right, I'm going to set my alarm for ten past eight. What time are you getting up, Tim?
Tim: Hmm, I think I'll set my alarm for, let's see, 8:09.

Ian: Oh, what lovely mashed potatoes! And just the right amount, too! Louis, are you not going to finish yours? Can't you manage them?
*Louis is stuffed and looks sick*
Ian: Well, I think I've just got room for some fruit! I'll have a satsuma.
Louis: Well in that case, I'll have a bag of satsumas.
*Louis proceeds to "down" a good ten satsumas*
by The T Meister October 27, 2005
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