"For Science!" was first used by Bonecrusher.  It was quickly picked up by Prime and Megatron, who decided that science needed to know if Wheeljack's tables are truly indestructible (they aren't when used on TC's head).  Since then, it’s become a common phrase, used by all, when something perks their curiosity and demands experimentation. 

(Bonecrusher hates that everyone else uses it.)

(But Bonecrusher hates everything. Except Blackout. He hates Blackout a little less than everything else.)

(Bonecrusher hates that you all make assumptions about what he does and does not hate.)