扯淡 is a common slang expression meaning 'bullshit' or 'nonsense.' 胡扯 means 'to talk rubbish.' The 'idle chat' meaning is extremely common in colloquial Chinese.
Left-side hand radical - the indexing radical, side-form of 手. Marks 扯 as a hand action: yanking, ripping, tugging. Same family of pulling/jerking verbs: 拉 (pull), 拽 (haul), 撕 (rip), 揪 (grab and pull). 扯 is the prototype 'tug forcefully' verb.
Right-side 止 supplies the sound - zhǐ shifting to chě in 扯 (notable initial change). 止 originally pictured a planted foot; in 扯 the contrast is vivid: hand tugging while foot stays planted = the bracing posture of pulling something hard. Phonetic family: 址 (site), 趾 (toe), 扯 itself.
