[QUOTE=TeamAyu2004;2959934]Well now im all interested...
I found a video where a guy is playing in 7/4 and it kinda sounds like the beginning of the song... but ayumi's song has a LOT more going on.
ahh yes I can kinda hear a similarity

so thats a possibility!
IsthisLOL? has offered another possibility as well: "7/4 is a time signature in music, it influences the pacing of the melody - you could compare it to the lenght of every stanza of a poem. The time signature decides, how many beats you play before you start a new line(in the case of 7/4 you would play 7 beats of the 1/4-note lenght)
However, Humming 7/4 is not written in a 7/4 time signature, instead, it constantly jumps between a 3/4 time signature(the one commonly used in a waltz) and 4/4 time signature(or "common time", the one sued in almost every Pop song) - that constant change is rather uncommon in Pop music(though Ayumi has done it in other songs before) so it's of a certain importance for the song - important enough to be included in the title.
So one would assume it's about humming/singing in this 7/4(or, in reality: 4/4 + 3/4) time signature - about having fun with music in a way. I think Ayumi tried being smart and fun with the title but...failed a bit" This is also an interesting possibility

I wish i could just ask Ayu myself... i would have a lot of questions for her!