sweatdrops

The series dates from 1998 and has the visual design and feel of comedy shows from around that time (think Slayers and you wouldn't be too far off the mark), and has a healthy reliance on visual cues such as sweatdrops and whatnot that give you a big pointer that the series is meant to be a comedy.

Mania News Feed Bryan Morton 2010

Things like sweatdrops and chibi-isms, they're a bit odd to western eyes, but decodable.

Four Decades of Fridays… part four | Comics Should Be Good! @ Comic Book Resources 2007

Rude swords and murderous weapons were shaped by the swarthy artisan, from whose reeking brow the sweatdrops rolled upon the hot metal, hissing as they evaporated.

The Planter's Northern Bride 1854

Generic looking animation is often a function of generic storytelling, and hopefully we will see more and more anime creators not always rely on the usual visual shorthand (sweatdrops, SD characters, etc).

AnimeBlogger.net Antenna 2010

Instead, it inherits the tradition of realistic art that the gekiga movement started, while boldly rejecting the expressionistic techniques that gekiga developed (panel frames extending beyond the page, super-dense motion lines, manga symbols (tl note: manpu, basically the sweatdrops and forehead veins we all know and love), standardized poses during action scenes, and so on).

Anime Nano! 2009