Most believe it'll be Sarah Palin flying into town, to endorse Trump.
The ironic thing (if it is her) is that Palin used the Tea Party ideals to reach her level of fame... and for the first time, there's a legit tea party candidate that fits EVERY conservative ideal (CRUZ). If Palin endorses the lifelong liberal Trump, it'd prove she doesn't give a shit about conservatism - all she cares about is celebrity and fame.
(I'm still thinking it's someone else... who else his super high profile that Trump'd make such a big deal about it)