When Umi and her sister go looking for the Literature club, they pass a few students who belong to the astronomy club.
"Why are there girls here? Do you think they want to date us?
The chemistry club students getting in a fight with the philosophy club student.
This exchange from the two person Archaeology Club in the English dub. The way the second line is said sells it:
"How can we make archaeology cool again?!"
Later in the scene, the same two guys jump up and run off to research the Paleolothic period, presumably the key to coolness.
In the same scene, when Shun mentions that he cut his hand shaving, Sora squees in the fangirliest voice possible ''"He shaves!"''
While leaving the clubhouse, Umi in her haste jostles two boys at the bottom of the stairs. Although not identified as Biology Club members, they say to each other "Check it out! X chromosome" as she runs out the door.
When the club members have a mass meeting, which results in them shouting at each other at once. Their look-out then shows up to warn them that some teachers are coming by, at which point the club members promptly organize themselves and start singing the school's anthem.