Slide Trombone
Slide Trombone
[Megan walking along carrying a trombone.] Offpanel voice #1: Hey, her old trombone. Offpanel voice #2: Cool, I haven't seen that thing since the 90s.
[Four quick shots of Megan moving the trombone's slide back and forth. It makes sound, but not like an ordinary trombone.] FX: Slide FX: Hisss FX: Slide FX: Hisss
[Megan does something else with the trombone, and it shoots water at the offpanel observers.] FX: Pshhhhh Offpanel voice #1: AUGH! Offpanel voice #2: So that's where my Super Soaker went.

In this comic, Megan carries her "old" trombone , a brass musical instrument with a movable sliding piece used to change a musical note's pitch, which those offscreen apparently haven't caught sight of since the 90s (presumably the 1990s). These offscreen people don't suspect anything unusual of Megan's trombone until it turns out that it contains a water gun, which she uses to soak the other characters. It is unclear whether she has somehow hidden the water gun inside the trombone, has disassembled it to produce a hybrid trombone/Super Soaker device, or otherwise modified the trombone such that it can shoot water as a water gun would.
In the second panel, she is priming the water gun by pumping air into it, following the sequence of pump actions used for the Super Soaker. During the first "slide" action, the user pulls the grip towards themselves, increasing pressure within the water reservoir of the gun. During the second "hiss" action, this grip is pushed away; a valve prevents air leaving the chamber, though a small amount usually leaks out. Part of the joke here is that a slide trombone also has a slide mechanism, held in a similar way as that of the Super Soaker, but which serves a completely different purpose. In the case of the trombone, when the slide is extended, the total length of tubing between the mouthpiece and the bell is extended, thereby lowering the pitch of the sound that is produced (there is, however, no comparable air chamber). This similarity between the two devices enables Megan to use the trombone's slide as if it were a Super Soaker's.
In the third panel, she presses the trigger, causing the compressed air within the water reservoir to push water from it at high speed, hitting the off-screen targets. One cries out in surprise, while the other expresses the realization of what had happened to their lost Super Soaker (that Megan had taken it as an alteration to her trombone).
In the title text, Megan asks those offscreen about the CPS 2000 , a water gun which, as is mentioned, was powerful but too powerful, causing injuries to those shot by it and allegedly leading to its discontinuation. Megan then, in connection with her previous question about the Super Soaker, asks to borrow a tuba, most probably to hide the CPS 2000 water gun inside. Her reasoning behind needing this tuba seems to be that the CPS 2000 is seemingly larger than the Super Soaker originally stored in Megan's trombone and thus would require a larger vessel (this use of the tuba may be cause for loss of friendship with an experienced player).
The CPS 2000 referenced by Megan was developed primarily by Lonnie Johnson (inventor) and Bruce D'Andrade for Larami 's Super Soaker product line. The "CPS" within its name refers to the " Constant Pressure System " used in certain water guns (its technology can be seen in this patent by Bruce D'Andrade). In this system, a rubber bladder within the water gun is pressurized by the user's pumping action, which draws water from a reservoir and pushes it into the pressure chamber, filling the bladder like a balloon. Once the desired volume of water is stored within the toy, the water can be released by means of a spring-loaded trigger and valve system. Upon release, the rubber bladder pushes the water out of the pressure chamber and out of the front nozzle, hitting whatever targets the user desires it to. The "constant pressure" of the CPS's name refers to the fact that the bladder will exert the same pressure on the water throughout the shot, ensuring consistent power and range, as opposed to air pressure Super Soakers, whose power will die off during the shot as the pressurized air within the pressure chamber expands, expelling the water but reducing the pressure in the toy.
The Super Soaker that Megan uses in this comic is also referenced in 220: Philosophy and 517: Marshmallow Gun . If the water gun featured in this comic is the same as that depicted in previous comics, it would likely be a Super Soaker 50 , the first widely available pressurized water gun. It could also be the less common but earlier model the Power Drencher or the later SS 50 Classic Series , Super Soaker S.E. , or the 20th anniversary SS 50 rerelease .
[Megan walking along carrying a trombone.] Offpanel voice #1: Hey, her old trombone. Offpanel voice #2: Cool, I haven't seen that thing since the 90s.
[Four quick shots of Megan moving the trombone's slide back and forth. It makes sound, but not like an ordinary trombone.] FX: Slide FX: Hisss FX: Slide FX: Hisss
[Megan does something else with the trombone, and it shoots water at the offpanel observers.] FX: Pshhhhh Offpanel voice #1: AUGH! Offpanel voice #2: So that's where my Super Soaker went.
