ウロウロ (uro uro)
“Uro uro” is not, technically, a sound effect. It can be written in hiragana rather than katakana as うろうろ because it is a native Japanese colloquialism. However, to differentiate it as a colloquialism, it is often written in katakana anyway, as I am doing here.
Here’s a quick run-down of how “uro uro” is used.
ウロウロする (uro uro suru) is the -suru verb form of “uro uro.”
“To uro uro” is to loiter, to wander aimlessly, and so forth.
If a mouse (鼠、ねずみ, nezumi) is ウロウロする (uro uro suru), the mouse is scurrying about.
If a little blond girl in a pretty pirate outfit is ウロウロする in a mansion searching for pirate treasure, she is roaming about as she searches.
In the above case, the girl was told by another character in the Japanese PS3 version of “Tales of Vesperia” that the mansion was no place for a little girl to be “uro uro suru” (uro uro-ing) in. That is, it was a quite dangerous place for a little girl to be, so she shouldn’t just wander around on her own.
If we used this as an adjective, we could have an ウロウロな話 (uro uro na hanashi), a meandering story, that is, a story that wanders from place to place, seemingly aimlessly.
That is how “uro uro” is used. As it is a commonly known colloquialism in Japan, it will appear in manga, video games, and so forth, without any regard for Japanese language learners.