Someone

bind notc - "knock-knock" notc:knock
bind bot - "handle_invite" bot:handle_invite
if {![info exists expired_invites]} {
    array set expired_invites {}
}

proc notc:knock {nick host hand text dest} {
    if {![validchan $dest]} {return 0} # notice to bot
    if {![botonchan $dest]} {return 0} # shouldn't occur
    if {![botisop $dest]} {return 0} # can't invite anyway

    utimer [rand 10] [list invite_person $nick $host $dest]
}

# called because some bot's utimer expired before this one's
proc bot:handle_invite {from cmd text} {
    set ::expired_invites([list $nick $host $chan]) 1
}

proc invite_person {nick host chan} {
    # check that we haven't already expired this.
    if {[info exists ::expired_invites([list $nick $host $chan])]} {
        unset ::expired_invites([list $nick $host $chan])
        return 0
    }
    putallbots "handle_invite $nick $host $chan" # I got this!!
    puthelp "INVITE $nick $chan"
}