[Carpetsmoker]

This is on FreeBSD 7

[/usr/src]% find . -type f -exec grep -EHi --color 'reboot.*\\n' {} \;
./cddl/contrib/opensolaris/cmd/dtrace/dtrace.c:         error("run update_drv(1M) or reboot to enable changes\n");
./sbin/fsck_ffs/main.c:                 printf("\n***** REBOOT NOW *****\n");
./sys/boot/common/panic.c:      printf("--> Press a key on the console to reboot <--\n");
./sys/boot/common/panic.c:      printf("Rebooting...\n");
./sys/boot/i386/loader/main.c:    printf("Rebooting...\n");
./sys/boot/pc98/cdboot/cdboot.s:msg_keypress:   .asciz "\r\nPress any key to reboot\r\n"
./sys/boot/pc98/loader/main.c:    printf("Rebooting...\n");
./sys/boot/sparc64/loader/main.c:       printf("Rebooting...\n");
./sys/dev/acpica/acpi_timer.c:    device_printf(acpi_timer_dev, "timer test in progress, reboot to quit.\n");
./sys/dev/dpt/dpt_scsi.c:                               printf("dpt%d: HBA rebooted.\n"
./sys/dev/ixgbe/ixgbe.c:                            "Please Reboot!!\n");
./sys/dev/mpt/mpt_cam.c:                    "effect until next reboot or IOC reset\n");
./sys/dev/mxge/if_mxge.c:               device_printf(sc->dev, "NIC rebooted, status = 0x%x\n",
./sys/dev/mxge/if_mxge.c:                             "NIC did not reboot, not resetting\n");
./sys/i4b/layer1/ihfc/i4b_ihfc_pnp.c:                                   "Please hard reboot your computer!\n",
./sys/i4b/layer1/ihfc/i4b_ihfc_pnp.c:   "A hard reboot may help!\n", unit);
./sys/kern/kern_shutdown.c:             printf("Please press any key to reboot.\n\n");
./sys/kern/kern_shutdown.c:             printf("--> Press a key on the console to reboot,\n");
./sys/kern/kern_shutdown.c:     printf("Rebooting...\n");
./usr.sbin/cron/lib/entry.c:                    Debug(DPARS, ("load_entry()...reboot shortcut\n"))
./usr.sbin/sysinstall/config.c:                      "the user intends to install themselves before rebooting\n"
./usr.sbin/sysinstall/config.c:          "reboot, or to enable xdm.  The default ttys file enables normal\n"
./usr.sbin/sysinstall/installUpgrade.c:                       "way that this upgrade process works, you will have to reboot\n"
./usr.sbin/sysinstall/main.c:       || !msgNoYes("Are you sure you wish to exit?  The system will reboot\n"
./usr.sbin/sysinstall/menus.c:    "installation.  If this is not the case then you should reboot\n"

As a piece of trivia, I also discovered that the function in shutdown.c that actually shuts down the system is called die_you_gravy_sucking_pig_dog() ...