You can do something like:

    printssh() {
        tte --input-file YOUR_FILE --frame-rate=500 $(echo "beams binarypath blackhole bouncyballs bubbles burn colorshift crumble decrypt errorcorrect expand fireworks middleout     orbittingvolley overflow pour print rain randomsequence rings scattered slice slide spotlights spray swarm synthgrid unstable vhstape waves wipe" | tr ' ' '\n' | shuf -n 1)
        ssh "$@"
    }
    alias ssh="printssh"

Anything in your ~/.bashrc or ~/.zshrc gets executed in sequence, so at the bottom of it I have

    /home/keeb/code/projects/login/motd.sh

And the contents of that file is...

    #!/usr/bin/env zsh

    values=("bubbles" "slide" "beams" "rain" "pour" "synthgrid" "unstable" "poop")
    len=${#values[@]}
    index=$(( (RANDOM % (len - 1)) + 1 ))
    selected=${values[$index]}
    cat /home/keeb/code/projects/login/motd | tte $selected