What does 「ひざっこぞうをたたいてみるよ」 mean?

Question

This is a line from the song 「結婚しようよ」by 吉田{よしだ}拓郎{たくろう} (youtube link)

Relevant piece of lyrics:

雨が上がって雲のきれ間に

お陽様さんが見えたら

ひざっこぞうをたたいてみるよ

結婚しようよMMMM

Source

When I googled it, I came across 膝を叩く which seems to be used when you "get" something (an element of surprise where you tap your knees to show it) but I don't think it has that meaning here.

Also, I could not find a proper meaning for ひざっこぞう but I could find a meaning for ひざこぞう (kneecap) which means the っ is probably used for emphasis.

Answer 1

First of all, your interpretation of 「ひざっこぞう」 is correct.

ひざっこぞう ＝ ひざこぞう ＝ ひざ ＝ most technically, ひざ頭{がしら}

By adding the こぞう（小僧）= "a little boy", it personifies the word 「ひざ」 = "kneecap".

Regarding the meaning of 「ひざっこぞうをたたいてみるよ」, I have always thought (in Japanese, of course, as I did not speak a word of English when this song came out) that it meant something along the lines of "I'll slap my thigh (and cavort around.)".

In other words, it means to me "I'll be saying 'This is it! I've gotta marry her (or propose to her)!'"