Heh heh heh. Oh Yang, I think you traumatized her, sweetie. Although the glass table is supposed to show Weiss's booty, putting weight on the glass could shatter if Yang got on Weiss's lap. We don't want the broken shards to cut the girls, now do we? Overall, the comic was pretty funny.
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The perspective in this piece makes some proportions a bit off. Yang's legs look unusually long. Not much is seen about Weiss other than her butt on the glass seat. Giving Weiss a more surprised look could make the humor more convincing.