The title is a clever double entendre. It refers to the physical used throughout the episode: the one Hank asks Walt to retrieve from Gus Fring’s car and, more pivotally, the one Walt secretly plants on Jesse’s car. It also alludes to the recurring "insect" motif in the series—representing everything from Walt’s mounting paranoia to the "infestation" of their criminal lives. Key Plot Developments
Skyler finds herself in a bind when her former boss, Ted Beneke , reveals he is being audited by the IRS. Fearing an audit of her own finances, she stages a convincing performance as a "clueless bookkeeper" to save him, but soon realizes Ted has no assets left to pay his debts.
In one of the most iconic "badass" moments for Gustavo Fring, he walks directly into a sniper's line of fire during a cartel attack on his distribution center. This act of defiance forces a temporary truce and a new demand: Jesse must go to Mexico to teach the cartel how to cook "blue meth".