Imoji released an app for Android users allowing "us" to send custom smilies via Text Message.
Link: https://play.google.com/store/apps/details?id=com.imojiapp.imoji.prod&hl=en
My main concern was that smilies were being sent as attachments instead of a smilie. It appears that this app solves that problem and I can send it to both Android and iPhone devices just fine.
I've yet to see how it works with older Android devices but here is the test I performed earlier on the Nexus 5:
Link: https://play.google.com/store/apps/details?id=com.imojiapp.imoji.prod&hl=en
My main concern was that smilies were being sent as attachments instead of a smilie. It appears that this app solves that problem and I can send it to both Android and iPhone devices just fine.
I've yet to see how it works with older Android devices but here is the test I performed earlier on the Nexus 5:

