10:47 AM PT -- We just got Mitt in D.C. who offered up an explanation as to why he plucked the candles off one by one -- and it's a legit reason -- dude just wanted to keep his staff healthy.

Mitt Romney's birthday got super freaky with lots of hot wax, Twinkies ... and his unique approach to blowing.

The Utah Senator turned 72 Tuesday, and his staff surprised him with a cake made of his "favorite snack," much to his delight. Check out the vid, though -- Mitt drops a quick dad joke ... then gets weird with it.

It's unclear why, but Romney takes his sweet time, removes each candle one by one ... and THEN blows it out.

Mitt's method doesn't seem very efficient, especially if anyone in his office has any place to be -- but he claims it rewards him with more than the customary single birthday wish.

On the upside ... less saliva to go around.