Call this shortstack all in?

[mustardo]

NL 100 6 max on Party, I have only been at the table for a couple of orbits so have no reads. Villain has just over $30 I have nearly a full buy in.

Dealt to Hero A [img]/images/graemlins/diamond.gif[/img]K [img]/images/graemlins/spade.gif[/img]
UTG calls [$1], MP calls [$1], CO folds, Hero raises [$5], SB calls [$4.50], BB folds, UTG calls [$4],MP folds.

** Dealing Flop ** [ J [img]/images/graemlins/club.gif[/img], K [img]/images/graemlins/heart.gif[/img], J [img]/images/graemlins/diamond.gif[/img] ]
SB is all-In for $25.90, UTG folds, Hero???

Does he really do this with a J? As a rule is this an easy call or an easy fold? What if his bet was bigger, say $50?

Ta for thoughts