One of the most fun aspects of the Japanese language is the use of onomatopoeia, even in speech, officially phenomimes and psychomimes, to denote emotions or feelings or simply used as shortcuts. It sounds ridiculous to start with but these are such fun that I often can’t help myself using them. Be warned that using some of the more esoteric ones will raise some eyebrows and possibly cast aspersions on your maturity or sexuality.
This is the sound of your heartbeat. If you are nervous and your heart beats quickly you can indicate so by saying “doki doki”.
Shiny, sparkly stuff. As in “kira kira little star”. Or if someone finally had a good wash and his face is all gleaming and shiny, or after you have viciously attacked your teeth with a toothbrush.
Officially, if one can speak of official translations, this is the sound a gun makes in comics, but can also be used to denote doing things in quick succession or “like a shot”, as it were. For example “just create these assets quickly and gan gan put them in the game.”
If you’re the kind of person to get terribly excited about things, you can tell your hapless compatriots by exclaiming “waku waku”. Holding up two balled fists in the air while keeping your elbows tucked in your side will complete the picture.
I always thought this was the sound a monkey makes in comics, but apparently it can also be used to denote excitement and general happiness.
If you have been starving yourself or it’s lunchtime you may want to tell whomever you are talking to how famished you are with “peko peko”. It’s the sound of your empty stomah screaming for immediate attention.
To be “pera pera” is every foreigner’s dream; to be fluent. Of course it can be used for any language but if you’re speaking Japanese and people tell you how “pera pera” you are it means your Japanese is pretty good. Remember though that your Japanese is only fluent if people stop telling you how good it is. “Pera pera” is somewhere midway between “Nihongo jouzu ne!” (“You’re very good at Japanese!”), which means you can just about say “hello” and “thank you”, and the absolute lack of compliments, which means you are truly fluent.
After you have soaked in a nice volcanically heated spring water bath your skin is smooth and lovely and “tsuru tsuru”; it denotes the smoothness to the touch. It can be said of many things, like a salaryman’s bald head or that strange rubber robot toy.
This dubious one is quite literally the sound a well-endowed woman makes when, say, jogging, or playing extreme volleyball on the beach of a tropical island. Very little imagination is needed here in understanding or using this particular onomatopoeia.
There are literally a “quite some” amount of these, so a quick Google search should provide you with countless more minutes of hilarity and confusion.